Mallostery: Filling a niche between quality and metabolic control [Lipids]
To be, or not to be … What determines the destruction of a protein in response to metabolic cues? In the current issue of JBC, Wangeline and Hampton shed new light on this existential question by studying the classic case of HMGCR (Hmg2 in yeast), the rate-limiting step in sterol synthesis, and find a metabolic cue that causes “allosteric misfolding” and subsequent destruction of the protein, a concept they name mallostery. (Source: Journal of Biological Chemistry)
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Ngee Kiat Chua, Andrew J. Brown Tags: Editors ' Picks Highlights Source Type: research

“Mallostery”—ligand-dependent protein misfolding enables physiological regulation by ERAD [Protein Structure and Folding]
HMG-CoA reductase (HMGR) undergoes regulated degradation as part of feedback control of the sterol pathway. In yeast, the stability of the HMGR isozyme Hmg2 is controlled by the 20-carbon isoprenoid geranylgeranyl pyrophosphate (GGPP). Increasing GGPP levels cause more efficient degradation by the HMG-CoA reductase degradation (HRD) pathway, allowing for feedback regulation of HMGR. The HRD pathway is critical for the endoplasmic reticulum (ER)-associated degradation (ERAD) of misfolded ER proteins. Here, we have explored GGPP's role in HRD-dependent Hmg2 degradation. We found that GGPP potently regulates Hmg2 levels in vi...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Margaret A. Wangeline, Randolph Y. Hampton Tags: Editors ' Picks Source Type: research

Pseudomonas aeruginosa pyoverdine maturation enzyme PvdP has a noncanonical domain architecture and affords insight into a new subclass of tyrosinases [Enzymology]
In conclusion, our work unravels the structural basis of PvdP's activity in PVD biosynthesis, observations that may inform structure-guided development of PvdP-specific inhibitors to manage P. aeruginosa infections. (Source: Journal of Biological Chemistry)
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Juliane Poppe, Joachim Reichelt, Wulf Blankenfeldt Tags: Editors ' Picks Source Type: research

Correction: Disulfide-crosslink scanning reveals prion-induced conformational changes and prion strain-specific structures of the pathological prion protein PrPSc. [Additions and Corrections]
VOLUME 293 (2018) PAGES 12730–12740PAGE 12730:A funding source was inadvertently omitted. The Takeda Science Foundation should have been acknowledged in the grant footnote. (Source: Journal of Biological Chemistry)
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Yuzuru Taguchi, Li Lu, Cristobal Marrero-Winkens, Hiroki Otaki, Noriyuki Nishida, Hermann M. Schatzl Tags: Additions and Corrections Source Type: research

Staphylococcus aureus counters phosphate limitation by scavenging wall teichoic acids from other staphylococci via the teichoicase GlpQ [Metabolism]
Staphylococcus aureus is part of the human nasal and skin microbiomes along with other bacterial commensals and opportunistic pathogens. Nutrients are scarce in these habitats, demanding effective nutrient acquisition and competition strategies. How S. aureus copes with phosphate limitation is still unknown. Wall teichoic acid (WTA), a polyol-phosphate polymer, could serve as a phosphate source, but whether S. aureus can utilize it during phosphate starvation remains unknown. S. aureus secretes a glycerophosphodiesterase, GlpQ, that cleaves a broad variety of glycerol-3-phosphate (GroP) headgroups of deacylated phospholipi...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Ana Maria Jorge, Jonathan Schneider, Sandra Unsleber, Guoqing Xia, Christoph Mayer, Andreas Peschel Tags: Microbiology Source Type: research

The homeobox transcription factor MSX2 partially mediates the effects of bone morphogenetic protein 4 (BMP4) on somatic cell reprogramming [Signal Transduction]
In conclusion, MSX2 partially mediates the effects of BMP4 signaling during reprogramming, improving our understanding of the role of BMP signaling in MET and of the connection between cell lineage specifiers such as MSX2 and GATA3 and pluripotency. (Source: Journal of Biological Chemistry)
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Lilong Lin, Lining Liang, Xiao Yang, Hao Sun, Yuan Li, Duanqing Pei, Hui Zheng Tags: Cell Biology Source Type: research

Mitochondria-targeted drugs stimulate mitophagy and abrogate colon cancer cell proliferation [Cell Biology]
Mutations in the KRAS proto-oncogene are present in 50% of all colorectal cancers and are increasingly associated with chemotherapeutic resistance to frontline biologic drugs. Accumulating evidence indicates key roles for overactive KRAS mutations in the metabolic reprogramming from oxidative phosphorylation to aerobic glycolysis in cancer cells. Here, we sought to exploit the more negative membrane potential of cancer cell mitochondria as an untapped avenue for interfering with energy metabolism in KRAS variant–containing and KRAS WT colorectal cancer cells. Mitochondrial function, intracellular ATP levels, cellular...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Kathleen A. Boyle, Jonathan Van Wickle, R. Blake Hill, Adriano Marchese, Balaraman Kalyanaraman, Michael B. Dwinell Tags: Molecular Bases of Disease Source Type: research

Mechanistic insights into the switch of {alpha}B-crystallin chaperone activity and self-multimerization [Molecular Biophysics]
αB-Crystallin (αBc) is a small heat shock protein that protects cells against abnormal protein aggregation and disease-related degeneration. αBc is also a major structural protein that forms polydisperse multimers that maintain the liquid-like property of the eye lens. However, the relationship and regulation of the two functions have yet to be explored. Here, by combining NMR spectroscopy and multiple biophysical approaches, we found that αBc uses a conserved β4/β8 surface of the central α-crystallin domain to bind α-synuclein and Tau proteins and prevent them from aggregating...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Zhenying Liu, Chuchu Wang, Yichen Li, Chunyu Zhao, Tongzhou Li, Dan Li, Shengnan Zhang, Cong Liu Tags: Protein Structure and Folding Source Type: research

X-ray structural analyses of azide-bound cytochrome c oxidases reveal that the H-pathway is critically important for the proton-pumping activity [Molecular Biophysics]
Cytochrome c oxidase (CcO) is the terminal oxidase of cellular respiration, reducing O2 to water and pumping protons. X-ray structural features have suggested that CcO pumps protons via a mechanism involving electrostatic repulsions between pumping protons in the hydrogen-bond network of a proton-conducting pathway (the H-pathway) and net positive charges created upon oxidation of an iron site, heme a (Fea2+), for reduction of O2 at another iron site, heme a3 (Fea32+). The protons for pumping are transferred to the hydrogen-bond network from the N-side via the water channel of the H-pathway. Back-leakage of protons to the ...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Atsuhiro Shimada, Keita Hatano, Hitomi Tadehara, Naomine Yano, Kyoko Shinzawa-Itoh, Eiki Yamashita, Kazumasa Muramoto, Tomitake Tsukihara, Shinya Yoshikawa Tags: Bioenergetics Source Type: research

Multiple S100 protein isoforms and C-terminal phosphorylation contribute to the paralog-selective regulation of nonmuscle myosin 2 filaments [Protein Structure and Folding]
Nonmuscle myosin 2 (NM2) has three paralogs in mammals, NM2A, NM2B, and NM2C, which have both unique and overlapping functions in cell migration, formation of cell–cell adhesions, and cell polarity. Their assembly into homo- and heterotypic bipolar filaments in living cells is primarily regulated by phosphorylation of the N-terminally bound regulatory light chain. Here, we present evidence that the equilibrium between these filaments and single NM2A and NM2B molecules can be controlled via S100 calcium-binding protein interactions and phosphorylation at the C-terminal end of the heavy chains. Furthermore, we show tha...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Peter Ecsedi, Neil Billington, Gyula Palfy, Gergő Gogl, Bence Kiss, Eva Bulyaki, Andrea Bodor, James R. Sellers, Laszlo Nyitray Tags: Protein Structure and Folding Source Type: research

Ectopic fibroblast growth factor receptor 1 promotes inflammation by promoting nuclear factor-{kappa}B signaling in prostate cancer cells [Signal Transduction]
Initiation of expression of fibroblast growth factor receptor 1 (FGFR1) concurrent with loss of FGFR2 expression is a well-documented event in the progression of prostate cancer (PCa). Although it is known that some FGFR isoforms confer advantages in cell proliferation and survival, the mechanism by which the subversion of different FGFR isoforms contributes to PCa progression is incompletely understood. Here, we report that fibroblast growth factor (FGF) promotes NF-κB signaling in PCa cells and that this increase is associated with FGFR1 expression. Disruption of FGFR1 kinase activity abrogated both FGF activity an...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Cong Wang, Yuepeng Ke, Shaoyou Liu, Sharon Pan, Ziying Liu, Hui Zhang, Zhichao Fan, Changyi Zhou, Junchen Liu, Fen Wang Tags: Cell Biology Source Type: research

Roles of distal aspartate and arginine of B-class dye-decolorizing peroxidase in heterolytic hydrogen peroxide cleavage [Protein Structure and Folding]
Dye-decolorizing peroxidases (DyPs) represent the most recently classified hydrogen peroxide–dependent heme peroxidase family. Although widely distributed with more than 5000 annotated genes and hailed for their biotechnological potential, detailed biochemical characterization of their reaction mechanism remains limited. Here, we present the high-resolution crystal structures of WT B-class DyP from the pathogenic bacterium Klebsiella pneumoniae (KpDyP) (1.6 Å) and the variants D143A (1.3 Å), R232A (1.9 Å), and D143A/R232A (1.1 Å). We demonstrate the impact of elimination of the DyP-typical, di...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Vera Pfanzagl, Kevin Nys, Marzia Bellei, Hanna Michlits, Georg Mlynek, Gianantonio Battistuzzi, Kristina Dȷinovic–Carugo, Sabine Van Doorslaer, Paul G. Furtmuller, Stefan Hofbauer, Christian Obinger Tags: Enzymology Source Type: research

TNF-{alpha} elicits phenotypic and functional alterations of vascular smooth muscle cells by miR-155-5p-dependent down-regulation of cGMP-dependent kinase 1 [Cell Biology]
cGMP-dependent protein kinase 1 (PKG1) plays an important role in nitric oxide (NO)/cGMP–mediated maintenance of vascular smooth muscle cell (VSMC) phenotype and vasorelaxation. Inflammatory cytokines, including tumor necrosis factor-α (TNFα), have long been understood to mediate several inflammatory vascular diseases. However, the underlying mechanism of TNFα-dependent inflammatory vascular disease is unclear. Here, we found that TNFα treatment decreased PKG1 expression in cultured VSMCs, which correlated with NF-κB–dependent biogenesis of miR-155-5p that targeted the 3′-UTR...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Seunghwan Choi, Minsik Park, Joohwan Kim, Wonjin Park, Suji Kim, Dong-Keon Lee, Jong Yun Hwang, Jongseon Choe, Moo-Ho Won, Sungwoo Ryoo, Kwon-Soo Ha, Young-Guen Kwon, Young-Myeong Kim Tags: Cell Biology Source Type: research

The Ras-like GTPase Rem2 is a potent inhibitor of calcium/calmodulin-dependent kinase II activity [Neurobiology]
Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a well-characterized, abundant protein kinase that regulates a diverse set of functions in a tissue-specific manner. For example, in heart muscle, CaMKII regulates Ca2+ homeostasis, whereas in neurons, CaMKII regulates activity-dependent dendritic remodeling and long-term potentiation (LTP), a neurobiological correlate of learning and memory. Previously, we identified the GTPase Rem2 as a critical regulator of dendrite branching and homeostatic plasticity in the vertebrate nervous system. Here, we report that Rem2 directly interacts with CaMKII and potently inhibits t...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Leandro Royer, Josiah J. Herzog, Katelyn Kenny, Boriana Tzvetkova, Jesse C. Cochrane, Michael T. Marr II, Suzanne Paradis Tags: Molecular Biophysics Source Type: research

Thylakoid membrane lipid sulfoquinovosyl-diacylglycerol (SQDG) is required for full functioning of photosystem II in Thermosynechococcus elongatus [Plant Biology]
Sulfoquinovosyl-diacylglycerol (SQDG) is one of the four lipids present in the thylakoid membranes. Depletion of SQDG causes different degrees of effects on photosynthetic growth and activities in different organisms. Four SQDG molecules bind to each monomer of photosystem II (PSII), but their role in PSII function has not been characterized in detail, and no PSII structure without SQDG has been reported. We analyzed the activities of PSII from an SQDG-deficient mutant of the cyanobacterium Thermosynechococcus elongatus by various spectroscopic methods, which showed that depletion of SQDG partially impaired the PSII activi...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Yoshiki Nakajima, Yasufumi Umena, Ryo Nagao, Kaichiro Endo, Koichi Kobayashi, Fusamichi Akita, Michihiro Suga, Hajime Wada, Takumi Noguchi, Jian-Ren Shen Tags: Bioenergetics Source Type: research

Aggregation-phase diagrams of {beta}2-microglobulin reveal temperature and salt effects on competitive formation of amyloids versus amorphous aggregates [Protein Structure and Folding]
Several serious diseases are associated with crystal-like amyloid fibrils or glass-like amorphous aggregates of denatured proteins. However, protein aggregation involving both types of aggregates has not yet been elucidated in much detail. Using a protein associated with dialysis-related amyloidosis, β2-microglobulin (β2m), we previously demonstrated that amyloid fibrils and amorphous aggregates form competitively depending on salt (NaCl) concentration. To examine the generality of the underlying competitive mechanisms, we herein investigated the effects of heat on acid-denatured β2m at pH 2. Using thioflavi...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Masayuki Adachi, Masahiro Noȷi, Masatomo So, Kenȷi Sasahara, Jozsef Kardos, Hironobu Naiki, Yuȷi Goto Tags: Protein Structure and Folding Source Type: research

Pharmacological induction of heat shock proteins ameliorates toxicity of mutant PKC{gamma} in spinocerebellar ataxia type 14 [Neurobiology]
Amyloid and amyloid-like protein aggregations are hallmarks of multiple, varied neurodegenerative disorders, including Alzheimer's and Parkinson's diseases. We previously reported that spinocerebellar ataxia type 14 (SCA14), a dominant-inherited neurodegenerative disease that affects cerebellar Purkinje cells, is characterized by the intracellular formation of neurotoxic amyloid-like aggregates of genetic variants of protein kinase Cγ (PKCγ). A number of protein chaperones, including heat shock protein 70 (Hsp70), promote the degradation and/or refolding of misfolded proteins and thereby prevent their aggregati...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Aoi Nakazono, Naoko Adachi, Hideyuki Takahashi, Takahiro Seki, Daizo Hamada, Takehiko Ueyama, Norio Sakai, Naoaki Saito Tags: Molecular Bases of Disease Source Type: research

Myc and ChREBP transcription factors cooperatively regulate normal and neoplastic hepatocyte proliferation in mice [Metabolism]
Analogous to the c-Myc (Myc)/Max family of bHLH-ZIP transcription factors, there exists a parallel regulatory network of structurally and functionally related proteins with Myc-like functions. Two related Myc-like paralogs, termed MondoA and MondoB/carbohydrate response element–binding protein (ChREBP), up-regulate gene expression in heterodimeric association with the bHLH-ZIP Max-like factor Mlx. Myc is necessary to support liver cancer growth, but not for normal hepatocyte proliferation. Here, we investigated ChREBP's role in these processes and its relationship to Myc. Unlike Myc loss, ChREBP loss conferred a prol...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Huabo Wang, James M. Dolezal, Sucheta Kulkarni, Jie Lu, Jordan Mandel, Laura E. Jackson, Frances Alencastro, Andrew W. Duncan, Edward V. Prochownik Tags: Gene Regulation Source Type: research

mTOR complex 1 controls the nuclear localization and function of glycogen synthase kinase 3{beta} [Signal Transduction]
Glycogen synthase kinase 3β (GSK3β) phosphorylates and thereby regulates a wide range of protein substrates involved in diverse cellular functions. Some GSK3β substrates, such as c-Myc and Snail, are nuclear transcription factors, suggesting the possibility that GSK3β function is controlled through its nuclear localization. Here, using ARPE-19 and MDA-MB-231 human cell lines, we found that inhibition of mTOR complex 1 (mTORC1) leads to partial redistribution of GSK3β from the cytosol to the nucleus and to a GSK3β-dependent reduction of the levels of both c-Myc and Snail. mTORC1 is known to be ...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Stephen J. Bautista, Ivan Boras, Adriano Vissa, Noa Mecica, Christopher M. Yip, Peter K. Kim, Costin N. Antonescu Tags: Cell Biology Source Type: research

AIF promotes a JNK1-mediated cadherin switch independently of respiratory chain stabilization [Signal Transduction]
Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein occasionally involved in cell death that primarily regulates mitochondrial energy metabolism under normal cellular conditions. AIF catalyzes the oxidation of NADH in vitro, yet the significance of this redox activity in cells remains unclear. Here, we show that through its enzymatic activity AIF is a critical factor for oxidative stress-induced activation of the mitogen-activated protein kinases JNK1 (c-Jun N-terminal kinase), p38, and ERK (extracellular signal-regulated kinase). AIF-dependent JNK1 signaling culminates in the cadherin switch, and genetic rever...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Andrew J. Scott, Sierra A. Walker, Joshua J. Krank, Amanda S. Wilkinson, Kaitlyn M. Johnson, Eric M. Lewis, John C. Wilkinson Tags: Cell Biology Source Type: research

Sialidase down-regulation reduces non-HDL cholesterol, inhibits leukocyte transmigration, and attenuates atherosclerosis in ApoE knockout mice [Glycobiology and Extracellular Matrices]
Atherosclerosis is a complex disease that involves alterations in lipoprotein metabolism and inflammation. Protein and lipid glycosylation events, such as sialylation, contribute to the development of atherosclerosis and are regulated by specific glycosidases, including sialidases. To evaluate the effect of the sialidase neuraminidase 1 (NEU1) on atherogenesis, here we generated apolipoprotein E (ApoE)-deficient mice that express hypomorphic levels of NEU1 (Neu1hypoApoe−/−). We found that the hypomorphic NEU1 expression in male Apoe−/− mice reduces serum levels of very-low-density lipoprotein (VLDL)...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Elizabeth J. White, Gabriel Gyulay, Šarka Lhotak, Magdalena M. Szewczyk, Taryne Chong, Mark T. Fuller, Omid Dadoo, Alison E. Fox–Robichaud, Richard C. Austin, Bernardo L. Trigatti, Suleiman A. Igdoura Tags: Molecular Bases of Disease Source Type: research

Agonistic {beta}-Klotho antibody mimics fibroblast growth factor 21 (FGF21) functions [Metabolism]
Fibroblast growth factor 21 (FGF21), an endocrine hormone in the FGF family, plays a critical role in regulating metabolic homeostasis and has emerged as a therapeutic target for metabolic diseases, including Type 2 diabetes mellitus. FGF21 functions through a receptor complex that consists of an FGF receptor (FGFR) and a co-receptor β-Klotho. Here, we identify and biochemically and structurally characterize 39F7, a high-affinity agonistic monoclonal antibody (mAb) against β-Klotho that mimics FGF21 function. The co-crystal structure of β-Klotho KL1 domain in complex with 39F7 Fab revealed that the recogniti...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Xiaoshan Min, Jennifer Weiszmann, Sheree Johnstone, Wei Wang, Xinchao Yu, William Romanow, Stephen Thibault, Yang Li, Zhulun Wang Tags: Protein Structure and Folding Source Type: research

Copper levels affect targeting of hypoxia-inducible factor 1{alpha} to the promoters of hypoxia-regulated genes [Cell Biology]
Hypoxia-inducible factor 1α (HIF-1α) is a transcription factor that regulates cellular responses to hypoxia. It controls the expression of both BCL2/adenovirus E1B 19-kDa protein–interacting protein 3 (BNIP3) and insulin-like growth factor 2 (IGF2). Previous studies have demonstrated that in hypoxia, copper is required for the expression of BNIP3 but not for that of IGF2. Here, using ChIP assays, computational analyses, luciferase reporter assays, and real-time quantitative RT-PCR, we sought to better understand how copper regulates the differential target gene selectivity of HIF-1α. Human umbilical...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Xiaojuan Liu, Wenjing Zhang, Zhijuan Wu, Yutao Yang, Y. James Kang Tags: Gene Regulation Source Type: research

Structural analyses reveal the mechanism of inhibition of influenza virus NS1 by two antiviral compounds [Protein Structure and Folding]
The influenza virus is a significant public health concern causing 250,000–500,000 deaths worldwide each year. Its ability to change quickly results in the potential for rapid generation of pandemic strains for which most individuals would have no antibody protection. This pandemic potential highlights the need for the continuous development of new drugs against influenza virus. As an essential component and well established virulence determinant, NS1 (nonstructural protein 1) of influenza virus is a highly prioritized target for the development of anti-influenza compounds. Here, we used NMR to determine that the NS1...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Alex B. Kleinpeter, Alexander S. Jureka, Sally M. Falahat, Todd J. Green, Chad M. Petit Tags: Protein Structure and Folding Source Type: research

Hierarchical control of interleukin 13 (IL-13) signals in lung fibroblasts by STAT6 and SOX11 [Signal Transduction]
In this study, we identified IL-13–induced transcriptional factors in lung fibroblasts using DNA microarrays in which SOX11 was included. Knockdown of SOX11 down-regulated expression of periostin and CCL26, both of which are known to be downstream molecules of IL-13, whereas enforced expression of SOX11 together with IL-13 stimulation enhanced expression of periostin. Moreover, we found that in DNA microarrays combining IL-13 induction and SOX11 knockdown there exist both SOX11-dependent and -independent molecules in IL-13–inducible molecules. In the former, many inflammation-related and fibrosis-related molecu...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Yasutaka Mitamura, Satoshi Nunomura, Yasuhiro Nanri, Kazuhiko Arima, Tomohito Yoshihara, Kosaku Komiya, Shogo Fukuda, Hiroaki Takatori, Hiroshi Nakajima, Masutaka Furue, Kenji Izuhara Tags: Immunology Source Type: research

Arginine 107 of yeast ATP synthase subunit g mediates sensitivity of the mitochondrial permeability transition to phenylglyoxal [Cell Biology]
Modification with arginine-specific glyoxals modulates the permeability transition (PT) of rat liver mitochondria, with inhibitory or inducing effects that depend on the net charge of the adduct(s). Here, we show that phenylglyoxal (PGO) affects the PT in a species-specific manner (inhibition in mouse and yeast, induction in human and Drosophila mitochondria). Following the hypotheses (i) that the effects are mediated by conserved arginine(s) and (ii) that the PT is mediated by the F-ATP synthase, we have narrowed the search to 60 arginines. Most of these residues are located in subunits α, β, γ, ϵ, a, an...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Lishu Guo, Michela Carraro, Geppo Sartori, Giovanni Minervini, Ove Eriksson, Valeria Petronilli, Paolo Bernardi Tags: Bioenergetics Source Type: research

14-3-3{gamma} binds regulator of G protein signaling 14 (RGS14) at distinct sites to inhibit the RGS14:G{alpha}i-AlF4- signaling complex and RGS14 nuclear localization [Neurobiology]
Regulator of G protein signaling 14 (RGS14) is a multifunctional brain scaffolding protein that integrates G protein and Ras/ERK signaling pathways. It is also a nucleocytoplasmic shuttling protein. RGS14 binds active Gαi/o via its RGS domain, Raf and active H-Ras–GTP via its R1 Ras-binding domain (RBD), and inactive Gαi1/3 via its G protein regulatory (GPR) domain. RGS14 suppresses long-term potentiation (LTP) in the CA2 region of the hippocampus, thereby regulating hippocampally based learning and memory. The 14-3-3 family of proteins is necessary for hippocampal LTP and associative learning and memory....
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Kyle J. Gerber, Katherine E. Squires, John R. Hepler Tags: Signal Transduction Source Type: research

The run-on oligomer filament enzyme mechanism of SgrAI: Part 2. Kinetic modeling of the full DNA cleavage pathway [Molecular Biophysics]
Filament or run-on oligomer formation by enzymes is now recognized as a widespread phenomenon with potentially unique enzyme regulatory properties and biological roles. SgrAI is an allosteric type II restriction endonuclease that forms run-on oligomeric filaments with activated DNA cleavage activity and altered DNA sequence specificity. In this two-part work, we measure individual steps in the run-on oligomer filament mechanism to address specific questions of cooperativity, trapping, filament growth mechanisms, and sequestration of activity using fluorophore-labeled DNA, kinetic FRET measurements, and reaction modeling wi...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Chad K. Park, Jonathan L. Sanchez, Claudia Barahona, L. Emilia Basantes, Juan Sanchez, Christian Hernandez, N. C. Horton Tags: Enzymology Source Type: research

The run-on oligomer filament enzyme mechanism of SgrAI: Part 1. Assembly kinetics of the run-on oligomer filament [Molecular Biophysics]
Filament or run-on oligomer formation by metabolic enzymes is now recognized as a widespread phenomenon having potentially unique enzyme regulatory properties and biological roles, and its dysfunction is implicated in human diseases such as cancer, diabetes, and developmental disorders. SgrAI is a bacterial allosteric type II restriction endonuclease that binds to invading phage DNA, may protect the host DNA from off-target cleavage activity, and forms run-on oligomeric filaments with enhanced DNA-cleavage activity and altered DNA sequence specificity. However, the mechanisms of SgrAI filament growth, cooperativity in fila...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Chad K. Park, Jonathan L. Sanchez, Claudia Barahona, L. Emilia Basantes, Juan Sanchez, Christian Hernandez, N. C. Horton Tags: Enzymology Source Type: research

The transcription factor NKX2-3 mediates p21 expression and ectodysplasin-A signaling in the enamel knot for cusp formation in tooth development [Gene Regulation]
Tooth morphogenesis is initiated by reciprocal interactions between the ectoderm and neural crest–derived mesenchyme. During tooth development, tooth cusps are regulated by precise control of proliferation of cell clusters, termed enamel knots, that are present among dental epithelial cells. The interaction of ectodysplasin-A (EDA) with its receptor, EDAR, plays a critical role in cusp formation by these enamel knots, and mutations of these genes is a cause of ectodermal dysplasia. It has also been reported that deficiency in Nkx2-3, encoding a member of the NK2 homeobox family of transcription factors, leads to cusp...
Source: Journal of Biological Chemistry - September 21, 2018 Category: Chemistry Authors: Xue Han, Keigo Yoshizaki, Kanako Miyazaki, Chieko Arai, Keita Funada, Tomomi Yuta, Tian Tian, Yuta Chiba, Kan Saito, Tsutomu Iwamoto, Aya Yamada, Ichiro Takahashi, Satoshi Fukumoto Tags: Developmental Biology Source Type: research

2019 Herbert Tabor Young Investigator Awards: Call for nominations [Editorials]
Recently, we announced an exciting change in our Herbert Tabor Young Investigator Awards program. Previously, these awards were given to young scientists for exemplary posters or talks at scientific meetings attended by JBC Associate Editors. Last year, we decided to focus instead on recognizing the first authors of outstanding papers published in JBC (1), with awards targeted to young investigators (including graduate students, postdoctoral scientists, and early stage junior faculty), whose work was published in JBC during 2017. A committee of JBC's Associate Editors selected five top papers, and the awardees (three postd...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: George N. DeMartino Tags: Editorials Source Type: research

An unlikely heme chaperone confirmed at last [Signal Transduction]
Labile heme, as opposed to heme that is tightly bound within proteins, is thought to require a chaperone to be trafficked within the cell due to its cytotoxicity, but the identity of this chaperone was not known. A new study reveals that an unlikely protein, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), is a heme chaperone that binds and transfers labile heme to downstream target proteins. These results provide a new framework for understanding heme homeostasis and raise intriguing questions regarding the intersection of heme transport, carbohydrate metabolism, and intracellular signaling. (Source: Journal of Biological Chemistry)
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Angela S. Fleischhacker, Stephen W. Ragsdale Tags: Editors ' Picks Highlights Source Type: research

Glyceraldehyde-3-phosphate dehydrogenase is a chaperone that allocates labile heme in cells [Molecular Biophysics]
Cellular heme is thought to be distributed between a pool of sequestered heme that is tightly bound within hemeproteins and a labile heme pool required for signaling and transfer into proteins. A heme chaperone that can hold and allocate labile heme within cells has long been proposed but never been identified. Here, we show that the glycolytic protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH) fulfills this role by acting as an essential repository and allocator of bioavailable heme to downstream protein targets. We identified a conserved histidine in GAPDH that is needed for its robust heme binding both in vitro an...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Elizabeth A. Sweeny, Anuradha Bharara Singh, Ritu Chakravarti, Osiris Martinez-Guzman, Arushi Saini, Mohammad Mahfuzul Haque, Greer Garee, Pablo D. Dans, Luciana Hannibal, Amit R. Reddi, Dennis J. Stuehr Tags: Editors ' Picks Source Type: research

Characterization of the molecular mechanism of the autophagy-related Atg8-Atg3 protein interaction in Toxoplasma gondii [Microbiology]
We reported previously that TgAtg8 and TgAtg3 interact directly. Here we validated that substitutions of conserved residues of TgAtg8 interacting with the Atg8 family–interacting motif (AIM) in Atg3 disrupt the TgAtg8–TgAtg3 interaction and reduce TgAtg8 lipidation and autophagosome formation. These findings were consistent with results reported previously for Plasmodium Atg8, suggesting functional conservation of Atg8 in Toxoplasma and Plasmodium. Moreover, using peptide and AlphaScreen assays, we identified the AIM sequence in TgAtg3 that binds TgAtg8. We determined that the core TgAtg3 AIM contains a Phe239-...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Shuxian Liu, Fangfei Zhang, Yan Wang, Han Wang, Xiaojian Chen, Yue Hu, Ming Chen, Shujue Lan, Chenhong Wang, Jiaxin Cao, Xin Hu, Feng Tan Tags: Molecular Biophysics Source Type: research

Defective mucin-type glycosylation on {alpha}-dystroglycan in COG-deficient cells increases its susceptibility to bacterial proteases [Molecular Bases of Disease]
Deficiency in subunits of the conserved oligomeric Golgi (COG) complex results in pleiotropic defects in glycosylation and causes congenital disorders in humans. Insight regarding the functional consequences of this defective glycosylation and the identity of specific glycoproteins affected is lacking. A chemical glycobiology strategy was adopted to identify the surface glycoproteins most sensitive to altered glycosylation in COG-deficient Chinese hamster ovary (CHO) cells. Following metabolic labeling, an unexpected increase in GalNAz incorporation into several glycoproteins, including α-dystroglycan (α-DG), w...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Seok-Ho Yu, Peng Zhao, Pradeep K. Prabhakar, Tiantian Sun, Aaron Beedle, Geert-Jan Boons, Kelley W. Moremen, Lance Wells, Richard Steet Tags: Glycobiology and Extracellular Matrices Source Type: research

The actin filament bundling protein {alpha}-actinin-4 actually suppresses actin stress fibers by permitting actin turnover [Cell Biology]
Cells organize actin filaments into contractile bundles known as stress fibers that resist mechanical stress, increase cell adhesion, remodel the extracellular matrix, and maintain tissue integrity. α-actinin is an actin filament bundling protein that is thought to be essential for stress fiber formation and stability. However, previous studies have also suggested that α-actinin might disrupt fibers, making the true function of this biomolecule unclear. Here we use fluorescence imaging to show that kidney epithelial cells depleted of α-actinin-4 via shRNA or CRISPR/Cas9, or expressing a disruptive mutant ...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: James Peter Kemp Jr., William M. Brieher Tags: Cell Biology Source Type: research

Conversion of all-trans-retinal into all-trans-retinal dimer reflects an alternative metabolic/antidotal pathway of all-trans-retinal in the retina [Metabolism]
In this study, we found that, after treatment of primary porcine RPE (pRPE) cells with atRAL, atRAL-dimer readily formed and accumulated in a concentration- and time-dependent manner, but A2E was barely detected. Cell-based assays revealed that atRAL, the precursor of atRAL-dimer, significantly altered the morphology of primary pRPE cells and decreased cell viability at a concentration of 80 μm regardless of light exposure. By contrast, atRAL-dimer was not cytotoxic and phototoxic to primary pRPE cells. Compared with atRAL and A2E, atRAL-dimer was more vulnerable to light, followed by the generation of its photocleaved ...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Zhan Gao, Yi Liao, Chao Chen, Chunyan Liao, Danxue He, Jingmeng Chen, Jianxing Ma, Zuguo Liu, Yalin Wu Tags: Metabolism Source Type: research

Interaction between DUE-B and Treslin is required to load Cdc45 on chromatin in human cells [Cell Biology]
A key step in the initiation of eukaryotic DNA replication is the binding of the activator protein Cdc45 to promote MCM helicase unwinding of the origin template. We show here that the c-myc origin DNA unwinding element-binding protein, DUE-B, interacts in HeLa cells with the replication initiation protein Treslin to allow Cdc45 loading onto chromatin. The chromatin loading of DUE-B and Treslin are mutually dependent, and the DUE-B–Treslin interaction is cell cycle–regulated to peak as cells exit G1 phase prior to the initiation of replication. The conserved C-terminal domain of DUE-B is required for its bindin...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Sumeet Poudel, Jianhong Yao, Michael G. Kemp, Michael Leffak Tags: DNA and Chromosomes Source Type: research

The Saccharomyces cerevisiae Hrq1 and Pif1 DNA helicases synergistically modulate telomerase activity in vitro [Enzymology]
Telomere length homeostasis is vital for maintaining genomic stability and is regulated by multiple factors, including telomerase activity and DNA helicases. The Saccharomyces cerevisiae Pif1 helicase was the first discovered catalytic inhibitor of telomerase, but recent experimental evidence suggests that Hrq1, the yeast homolog of the disease-linked human RecQ-like helicase 4 (RECQL4), plays a similar role via an undefined mechanism. Using yeast extracts enriched for telomerase activity and an in vitro primer extension assay, here we determined the effects of recombinant WT and inactive Hrq1 and Pif1 on total telomerase ...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: David G. Nickens, Cody M. Rogers, Matthew L. Bochman Tags: DNA and Chromosomes Source Type: research

Structure-function analyses reveal the mechanism of the ARH3-dependent hydrolysis of ADP-ribosylation [Protein Structure and Folding]
ADP-ribosylation of proteins plays key roles in multiple biological processes, including DNA damage repair. Recent evidence suggests that serine is an important acceptor for ADP-ribosylation, and that serine ADP-ribosylation is hydrolyzed by ADP-ribosylhydrolase 3 (ARH3 or ADPRHL2). However, the structural details in ARH3-mediated hydrolysis remain elusive. Here, we determined the structure of ARH3 in a complex with ADP-ribose (ADPR). Our analyses revealed a group of acidic residues in ARH3 that keep two Mg2+ ions at the catalytic center for hydrolysis of Ser-linked ADP-ribosyl group. In particular, dynamic conformational ...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Mengxi Wang, Zenglin Yuan, Rong Xie, Yinliang Ma, Xiuhua Liu, Xiaochun Yu Tags: DNA and Chromosomes Source Type: research

The MST4-MOB4 complex disrupts the MST1-MOB1 complex in the Hippo-YAP pathway and plays a pro-oncogenic role in pancreatic cancer [Cell Biology]
The mammalian STE20-like protein kinase 1 (MST1)–MOB kinase activator 1 (MOB1) complex has been shown to suppress the oncogenic activity of Yes-associated protein (YAP) in the mammalian Hippo pathway, which is involved in the development of multiple tumors, including pancreatic cancer (PC). However, it remains unclear whether other MST–MOB complexes are also involved in regulating Hippo–YAP signaling and have potential roles in PC. Here, we report that mammalian STE20-like kinase 4 (MST4), a distantly related ortholog of the MST1 kinase, forms a complex with MOB4 in a phosphorylation-dependent manner. We ...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Min Chen, Hui Zhang, Zhubing Shi, Yehua Li, Xiaoman Zhang, Ziyang Gao, Li Zhou, Jian Ma, Qi Xu, Jingmin Guan, Yunfeng Cheng, Shi Jiao, Zhaocai Zhou Tags: Molecular Biophysics Source Type: research

Role of a conserved glutamine in the function of voltage-gated Ca2+ channels revealed by a mutation in human CACNA1D [Molecular Biophysics]
Voltage-gated Cav Ca2+ channels play crucial roles in regulating gene transcription, neuronal excitability, and synaptic transmission. Natural or pathological variations in Cav channels have yielded rich insights into the molecular determinants controlling channel function. Here, we report the consequences of a natural, putatively disease-associated mutation in the CACNA1D gene encoding the pore-forming Cav1.3 α1 subunit. The mutation causes a substitution of a glutamine residue that is highly conserved in the extracellular S1–S2 loop of domain II in all Cav channels with a histidine and was identified by whole...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Edgar Garza-Lopez, Josue A. Lopez, Jussara Hagen, Ruth Sheffer, Vardiella Meiner, Amy Lee Tags: Membrane Biology Source Type: research

Set4 is a chromatin-associated protein, promotes survival during oxidative stress, and regulates stress response genes in yeast [DNA and Chromosomes]
The Set4 protein in the yeast Saccharomyces cerevisiae contains both a PHD finger and a SET domain, a common signature of chromatin-associated proteins, and shares sequence homology with the yeast protein Set3, the fly protein UpSET, and the human protein mixed-lineage leukemia 5 (MLL5). However, the biological role for Set4 and its potential function in chromatin regulation has not been well defined. Here, we analyzed yeast cell phenotypes associated with loss of Set4 or its overexpression, which revealed that Set4 protects against oxidative stress induced by hydrogen peroxide. Gene expression analysis indicated that Set4...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Khoa Tran, Yogita Jethmalani, Deepika Jaiswal, Erin M. Green Tags: Gene Regulation Source Type: research

Microphthalmia-associated transcription factor up-regulates acetylcholinesterase expression during melanogenesis of murine melanoma cells [Neurobiology]
Acetylcholinesterase (AChE) hydrolyzes the neurotransmitter acetylcholine in neurons. However, AChE has been proposed to also have nonneuronal functions in different cell types. Here, we report that AChE is expressed in melanocytes and melanoma cells, and that the tetrameric (G4) form is the major AChE isoform in these cells. During melanogenesis of B16F10 murine melanoma cells, AChE levels decreased markedly. The differentiation of melanoma cells led to (i) an increase in melanin and tyrosinase, (ii) a change in intracellular cAMP levels, and (iii) a decrease in microphthalmia-associated transcription factor (MITF). We hy...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Qiyun Wu, Aster H. Y. Fung, Miranda L. Xu, Kaman Poon, Etta Y. L. Liu, Xiang P. Kong, Ping Yao, Qing P. Xiong, Tina T. X. Dong, Karl W. K. Tsim Tags: Cell Biology Source Type: research

The tumor suppressor protein DLC1 maintains protein kinase D activity and Golgi secretory function [Computational Biology]
Many newly synthesized cellular proteins pass through the Golgi complex from where secretory transport carriers sort them to the plasma membrane and the extracellular environment. The formation of these secretory carriers at the trans-Golgi network is promoted by the protein kinase D (PKD) family of serine/threonine kinases. Here, using mathematical modeling and experimental validation of the PKD activation and substrate phosphorylation kinetics, we reveal that the expression level of the PKD substrate deleted in liver cancer 1 (DLC1), a Rho GTPase–activating protein that is inhibited by PKD-mediated phosphorylation,...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Antje Jensch, Yannick Frey, Katharina Bitschar, Patrick Weber, Simone Schmid, Angelika Hausser, Monilola A. Olayioye, Nicole E. Radde Tags: Cell Biology Source Type: research

TRPM7 channels play a role in high glucose-induced endoplasmic reticulum stress and neuronal cell apoptosis [Signal Transduction]
High-glucose (HG) levels and hyperglycemia associated with diabetes are known to cause neuronal damage. The detailed molecular mechanisms, however, remain to be elucidated. Here, we investigated the role of transient receptor potential melastatin 7 (TRPM7) channels in HG-mediated endoplasmic reticulum stress (ERS) and injury of NS20Y neuronal cells. The cells were incubated in the absence or presence of HG for 48 h. We found that mRNA and protein levels of TRPM7 and of ERS-associated proteins, such as C/EBP homologous protein (CHOP), 78-kDa glucose-regulated protein (GRP78), and inducible nitric-oxide synthase (iNOS), incr...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Yan Huang, Tian-Dong Leng, Koichi Inoue, Tao Yang, Mingli Liu, F. David Horgen, Andrea Fleig, Jun Li, Zhi-Gang Xiong Tags: Molecular Bases of Disease Source Type: research

Protection of telomeres 1 proteins POT1a and POT1b can repress ATR signaling by RPA exclusion, but binding to CST limits ATR repression by POT1b [DNA and Chromosomes]
Comprised of telomeric TTAGGG repeats and shelterin, telomeres ensure that the natural ends of chromosomes remain impervious to the DNA damage response. Telomeres carry a long constitutive 3′ overhang that can bind replication protein A (RPA) and activate the ATR Ser/Thr kinase (ATR), which induces cell cycle arrest. A single-stranded (ss) TTAGGG repeat–binding protein in mouse shelterin, POT1a, has been proposed to repress ATR signaling by preventing RPA binding. Repression of ATR at telomeres requires tethering of POT1a to the other shelterin subunits situated on the double-stranded (ds) telomeric DNA. The si...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Katja Kratz, Titia de Lange Tags: Cell Biology Source Type: research

Domains with highest heparan sulfate-binding affinity reside at opposite ends in BMP2/4 versus BMP5/6/7: Implications for function [Signal Transduction]
Signaling proteins, including bone morphogenetic proteins (BMPs), specifically interact with heparan sulfate (HS). These interactions regulate protein distribution and function and are largely mediated by domains rich in basic amino acids. The N-terminal region of BMP2 and BMP4 contains one such domain with a typical Cardin-Weintraub (CW) motif, but it is unclear whether the same occurs in BMP5, BMP6, and BMP7 that constitute a separate evolutionary subgroup. Peptides spanning the N-terminal domain of BMP2/4 interacted with substrate-bound HS with nanomolar affinity, but peptides spanning BMP5/6/7 N-terminal domain did not...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Paul C. Billings, Evan Yang, Christina Mundy, Maurizio Pacifici Tags: Glycobiology and Extracellular Matrices Source Type: research

Secretion of misfolded cytosolic proteins from mammalian cells is independent of chaperone-mediated autophagy [Cell Biology]
In eukaryotic cells, elimination of misfolded proteins is essential for maintaining protein homeostasis and cell viability. Misfolding-associated protein secretion (MAPS) is a protein quality-control mechanism that exports misfolded cytosolic proteins via a compartment characteristic of late endosomes, but how cytosolic proteins enter this compartment is unclear. Because chaperone-mediated autophagy (CMA) is a known mechanism that imports cytosolic proteins bearing a specific CMA motif to lysosomes for degradation and because late endosomes and lysosomes overlap significantly in mammalian cells, we determined here whether ...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Juhyung Lee, Yue Xu, Ting Zhang, Lei Cui, Layla Saidi, Yihong Ye Tags: Cell Biology Source Type: research

PTE, a novel module to target Polycomb Repressive Complex 1 to the human cyclin D2 (CCND2) oncogene [DNA and Chromosomes]
Polycomb group proteins are essential epigenetic repressors. They form multiple protein complexes of which two kinds, PRC1 and PRC2, are indispensable for repression. Although much is known about their biochemical properties, how mammalian PRC1 and PRC2 are targeted to specific genes is poorly understood. Here, we establish the cyclin D2 (CCND2) oncogene as a simple model to address this question. We provide the evidence that the targeting of PRC1 to CCND2 involves a dedicated PRC1-targeting element (PTE). The PTE appears to act in concert with an adjacent cytosine-phosphate-guanine (CpG) island to arrange for the robust b...
Source: Journal of Biological Chemistry - September 14, 2018 Category: Chemistry Authors: Sarina R. Cameron, Soumyadeep Nandi, Tatyana G. Kahn, Juan I. Barrasa, Per Stenberg, Yuri B. Schwartz Tags: Gene Regulation Source Type: research