Ribavirin-induced down-regulation of CCAAT/enhancer-binding protein {alpha} leads to suppression of lipogenesis
Recently, we demonstrated that the anti-viral drug ribavirin (RBV) had the ability to suppress lipogenesis through down-regulation of retinoid X receptor α (RXRα) under the control of the intracellular GTP-level and AMP-activated protein kinase-related kinases, especially microtubule affinity regulating kinase 4 (MARK4). RXRα-overexpression attenuated but did not abolish lipogenesis suppression by RBV, implying that additional factor(s) were involved in this suppressive effect. In the present study, we found that the protein level, but not the mRNA level, of CCAAT/enhancer-binding protein α (C/EBP&a...
Source: Biochemical Journal - January 15, 2019 Category: Biochemistry Authors: Satoh, S., Onomura, D., Ueda, Y., Dansako, H., Honda, M., Kaneko, S., Kato, N. Tags: Research Articles Source Type: research
Mechanism of metal ion-induced activation of a two-component sensor kinase
Two-component systems (TCSs) are essential for bacteria to sense, respond, and adapt to changing environments, such as elevation of Cu(I)/Ag(I) ions in the periplasm. In Escherichia coli, the CusS–CusR TCS up-regulates the cusCFBA genes under increased periplasmic Cu(I)/Ag(I) concentrations to help maintain metal ion homeostasis. The CusS histidine kinase is a homodimeric integral membrane protein that binds to periplasmic Cu(I)/Ag(I) and transduces a signal to its cytoplasmic kinase domain. However, the mechanism of how metal binding in the periplasm activates autophosphorylation in the cytoplasm is unknown. Here, w...
Source: Biochemical Journal - January 15, 2019 Category: Biochemistry Authors: Affandi, T., McEvoy, M. M. Tags: Research Articles Source Type: research
New structural insights into anomeric carbohydrate recognition by frutalin: an {alpha}-D-galactose-binding lectin from breadfruit seeds
Frutalin (FTL) is a multiple-binding lectin belonging to the jacalin-related lectin (JRL) family and derived from Artocarpus incisa (breadfruit) seeds. This lectin specifically recognizes and binds α-d-galactose. FTL has been successfully used in immunobiological research for the recognition of cancer-associated oligosaccharides. However, the molecular bases by which FTL promotes these specific activities remain poorly understood. Here, we report the whole 3D structure of FTL for the first time, as determined by X-ray crystallography. The obtained crystals diffracted to 1.81 Å (Apo-frutalin) and 1.65 Å (f...
Source: Biochemical Journal - January 11, 2019 Category: Biochemistry Authors: Vieira Neto, A. E., de Sousa, F. D., Pereira, H. D., Moreno, F. B. M. B., Lourenzoni, M. R., Grangeiro, T. B., Monteiro Moreira, A. C. d. O., Moreira, R. d. A. Tags: Research Articles Source Type: research
Glycerol-3-phosphate acyltransferases 3 and 4 direct glycerolipid synthesis and affect functionality in activated macrophages
Macrophage classical M1 activation via TLR4 triggers a variety of responses to achieve the elimination of foreign pathogens. During this process, there is also an increase in lipid droplets which contain large quantities of triacylglycerol (TAG) and phospholipid (PL). The functional consequences of this increment in lipid mass are poorly understood. Here, we studied the contribution of glycerolipid synthesis to lipid accumulation, focusing specifically on the first and rate-limiting enzyme of the pathway: glycerol-3-phosphate acyltransferase (GPAT). Using bone marrow-derived macrophages (BMDMs) treated with Kdo2-lipid A, w...
Source: Biochemical Journal - January 11, 2019 Category: Biochemistry Authors: Quiroga, I. Y., Pellon-Maison, M., Suchanek, A. L., Coleman, R. A., Gonzalez-Baro, M. R. Tags: Research Articles Source Type: research
Using backbone-cyclized Cys-rich polypeptides as molecular scaffolds to target protein-protein interactions
The use of disulfide-rich backbone-cyclized polypeptides, as molecular scaffolds to design a new generation of bioimaging tools and drugs that are potent and specific, and thus might have fewer side effects than traditional small-molecule drugs, is gaining increasing interest among the scientific and in the pharmaceutical industries. Highly constrained macrocyclic polypeptides are exceptionally more stable to chemical, thermal and biological degradation and show better biological activity when compared with their linear counterparts. Many of these relatively new scaffolds have been also found to be highly tolerant to seque...
Source: Biochemical Journal - January 11, 2019 Category: Biochemistry Authors: Chaudhuri, D., Aboye, T., Camarero, J. A. Tags: Review Articles Source Type: research
Structure and nucleotide-induced conformational dynamics of the Chlorobium tepidum Roco protein
The LRR (leucine-rich repeat)–Roc (Ras of complex proteins)–COR (C-terminal of Roc) domains are central to the action of nearly all Roco proteins, including the Parkinson's disease-associated protein LRRK2 (leucine-rich repeat kinase 2). We previously demonstrated that the Roco protein from Chlorobium tepidum (CtRoco) undergoes a dimer–monomer cycle during the GTPase reaction, with the protein being mainly dimeric in the nucleotide-free and GDP (guanosine-5'-diphosphate)-bound states and monomeric in the GTP (guanosine-5'-triphosphate)-bound state. Here, we report a crystal structure of CtRoco in the nucl...
Source: Biochemical Journal - January 7, 2019 Category: Biochemistry Authors: Deyaert, E., Leemans, M., Singh, R. K., Gallardo, R., Steyaert, J., Kortholt, A., Lauer, J., Versees, W. Tags: Research Articles Source Type: research
Camelid single-domain antibodies raised by DNA immunization are potent inhibitors of EGFR signaling
Up-regulation of epidermal growth factor receptor (EGFR) is a hallmark of many solid tumors, and inhibition of EGFR signaling by small molecules and antibodies has clear clinical benefit. Here, we report the isolation and functional characterization of novel camelid single-domain antibodies (sdAbs or VHHs) directed against human EGFR. The source of these VHHs was a llama immunized with cDNA encoding human EGFR ectodomain alone (no protein or cell boost), which is notable in that genetic immunization of large, outbred animals is generally poorly effective. The VHHs targeted multiple sites on the receptor's surface with high...
Source: Biochemical Journal - January 7, 2019 Category: Biochemistry Authors: Rossotti, M. A., Henry, K. A., van Faassen, H., Tanha, J., Callaghan, D., Hussack, G., Arbabi-Ghahroudi, M., MacKenzie, C. R. Tags: Research Articles Source Type: research
Strangers in strange lands: mitochondrial proteins found at extra-mitochondrial locations
The mitochondrial proteome is estimated to contain ~1100 proteins, the vast majority of which are nuclear-encoded, with only 13 proteins encoded by the mitochondrial genome. The import of these nuclear-encoded proteins into mitochondria was widely believed to be unidirectional, but recent discoveries have revealed that many these ‘mitochondrial’ proteins are exported, and have extra-mitochondrial activities divergent from their mitochondrial function. Surprisingly, three of the exported proteins discovered thus far are mitochondrially encoded and have significantly different extra-mitochondrial roles than those...
Source: Biochemical Journal - January 7, 2019 Category: Biochemistry Authors: Scanlon, D. P., Salter, M. W. Tags: Review Articles Source Type: research
Understanding phosphoinositides: rare, dynamic, and essential membrane phospholipids
Polyphosphoinositides (PPIs) are essential phospholipids located in the cytoplasmic leaflet of eukaryotic cell membranes. Despite contributing only a small fraction to the bulk of cellular phospholipids, they make remarkable contributions to practically all aspects of a cell's life and death. They do so by recruiting cytoplasmic proteins/effectors or by interacting with cytoplasmic domains of membrane proteins at the membrane–cytoplasm interface to organize and mold organelle identity. The present study summarizes aspects of our current understanding concerning the metabolism, manipulation, measurement, and intimate ...
Source: Biochemical Journal - January 7, 2019 Category: Biochemistry Authors: Dickson, E. J., Hille, B. Tags: Review Articles Source Type: research
The multifunctional role of phospho-calmodulin in pathophysiological processes
Calmodulin (CaM) is a versatile Ca2+-sensor/transducer protein that modulates hundreds of enzymes, channels, transport systems, transcription factors, adaptors and other structural proteins, controlling in this manner multiple cellular functions. In addition to its capacity to regulate target proteins in a Ca2+-dependent and Ca2+-independent manner, the posttranslational phosphorylation of CaM by diverse Ser/Thr- and Tyr-protein kinases has been recognized as an important additional manner to regulate this protein by fine-tuning its functionality. In this review, we shall cover developments done in recent years in which ph...
Source: Biochemical Journal - December 21, 2018 Category: Biochemistry Authors: Villalobo, A. Tags: Review Articles Source Type: research
HDAC1 overexpression enhances {beta}-cell proliferation by down-regulating Cdkn1b/p27
The homeobox transcription factor Nkx6.1 is sufficient to increase functional β-cell mass, where functional β-cell mass refers to the combination of β-cell proliferation, glucose-stimulated insulin secretion (GSIS) and β-cell survival. Here, we demonstrate that the histone deacetylase 1 (HDAC1), which is an early target of Nkx6.1, is sufficient to increase functional β-cell mass. We show that HDAC activity is necessary for Nkx6.1-mediated proliferation, and that HDAC1 is sufficient to increase β-cell proliferation in primary rat islets and the INS-1 832/13 β-cell line. The increase in HDA...
Source: Biochemical Journal - December 19, 2018 Category: Biochemistry Authors: Draney, C., Austin, M. C., Leifer, A. H., Smith, C. J., Kener, K. B., Aitken, T. J., Hess, K. H., Haines, A. C., Lett, L. A., Hernandez-Carretero, A., Fueger, P. T., Arlotto, M., Tessem, J. S. Tags: Research Articles Source Type: research
CosR is an oxidative stress sensing a MarR-type transcriptional repressor in Corynebacterium glutamicum
The MarR family is unique to both bacteria and archaea. The members of this family, one of the most prevalent families of transcriptional regulators in bacteria, enable bacteria to adapt to changing environmental conditions, such as the presence of antibiotics, toxic chemicals, or reactive oxygen species (ROS), mainly by thiol-disulfide switches. Although the genome of Corynebacterium glutamicum encodes a large number of the putative MarR-type transcriptional regulators, their physiological and biochemical functions have so far been limited to only two proteins, regulator of oxidative stress response RosR and quinone oxido...
Source: Biochemical Journal - December 19, 2018 Category: Biochemistry Authors: Si, M., Chen, C., Su, T., Che, C., Yao, S., Liang, G., Li, G., Yang, G. Tags: Research Articles Source Type: research
Structural enzymology reveals the molecular basis of substrate regiospecificity and processivity of an exemplar bacterial glycoside hydrolase family 74 endo-xyloglucanase
Paenibacillus odorifer produces a single multimodular enzyme containing a glycoside hydrolase (GH) family 74 module (AIQ73809). Recombinant production and characterization of the GH74 module (PoGH74cat) revealed a highly specific, processive endo-xyloglucanase that can hydrolyze the polysaccharide backbone at both branched and unbranched positions. X-ray crystal structures obtained for the free enzyme and oligosaccharide complexes evidenced an extensive hydrophobic binding platform — the first in GH74 extending from subsites –4 to +6 — and unique mobile active-site loops. Site-directed mutagenesis reveale...
Source: Biochemical Journal - December 19, 2018 Category: Biochemistry Authors: Arnal, G., Stogios, P. J., Asohan, J., Skarina, T., Savchenko, A., Brumer, H. Tags: Research Articles Source Type: research
Structure of the sensory domain of McpX from Sinorhizobium meliloti, the first known bacterial chemotactic sensor for quaternary ammonium compounds
The α-proteobacterium Sinorhizobium meliloti can live freely in the soil or engage in a symbiosis with its legume host. S. meliloti facilitates nitrogen fixation in root nodules, thus providing pivotal, utilizable nitrogen to the host. The organism has eight chemoreceptors, namely McpT to McpZ and IcpA that facilitate chemotaxis. McpX is the first known bacterial sensor of quaternary ammonium compounds (QACs) such as choline and betaines. Because QACs are exuded at chemotaxis-relevant concentrations by germinating alfalfa seeds, McpX has been proposed to contribute to host-specific chemotaxis. We have determined the ...
Source: Biochemical Journal - December 14, 2018 Category: Biochemistry Authors: Shrestha, M., Compton, K. K., Mancl, J. M., Webb, B. A., Brown, A. M., Scharf, B. E., Schubot, F. D. Tags: Research Articles Source Type: research
Hypertrophic cardiomyopathy-linked variants of cardiac myosin-binding protein C3 display altered molecular properties and actin interaction
The most common inherited cardiac disorder, hypertrophic cardiomyopathy (HCM), is characterized by thickening of heart muscle, for which genetic mutations in cardiac myosin-binding protein C3 (c-MYBPC3) gene, is the leading cause. Notably, patients with HCM display a heterogeneous clinical presentation, onset and prognosis. Thus, delineating the molecular mechanisms that explain how disparate c-MYBPC3 variants lead to HCM is essential for correlating the impact of specific genotypes on clinical severity. Herein, five c-MYBPC3 missense variants clinically associated with HCM were investigated; namely V1 (R177H), V2 (A216T),...
Source: Biochemical Journal - December 14, 2018 Category: Biochemistry Authors: Da'as, S. I., Fakhro, K., Thanassoulas, A., Krishnamoorthy, N., Saleh, A., Calver, B. L., Safieh-Garabedian, B., Toft, E., Nounesis, G., Lai, F. A., Nomikos, M. Tags: Research Articles Source Type: research
