The catalytic mechanism for NO production by the mitochondrial enzyme, sulfite oxidase
Recently, Guenter Schwarz and colleagues published an elegant study in the Biochemical Journal (2019) 476, 1805–1815 which combines kinetic and spectroscopic studies with protein engineering to provide a mechanism for sulfite oxidase (SO)-catalyzed nitrite reduction that yields nitric oxide (NO). This work is noteworthy as it demonstrates that (i) for NO generation, both sulfite and nitrite must bind to the same molybdenum (Mo) center; (ii) upon sulfite reduction, Mo is reduced from +6 (MoVI) to +4 (MoIV) and MoIV reduces nitrite to NO yielding MoV; (iii) the heme moiety, linked to the Mo-center by an 11 amino acid r...
Source: Biochemical Journal - July 14, 2019 Category: Biochemistry Authors: Mutus, B. Tags: Commentaries Source Type: research
Metabolic remodeling of cardiomyocytes identified in phosphoinositide-dependent kinase 1-deficient mice
Metabolic remodeling plays an essential role in the pathophysiology of heart failure (HF). Many studies have shown that the disruption of phosphoinositide-dependent protein kinase-1 (PDK1) caused severe and lethal HF; however, the metabolic pattern of PDK1 deletion remains ambiguous. 1H nuclear magnetic resonance-based metabolomics was applied to explore the altered metabolic pattern in Pdk1-deficient mice. Principle component analysis showed significant separation as early as 4 weeks of age, and dysfunction of metabolism precedes a morphological change in Pdk1-deficient mice. A time trajectory plot indicated that disturbe...
Source: Biochemical Journal - July 8, 2019 Category: Biochemistry Authors: Li, C., Niu, Y., Zheng, H., Shan, C., Chen, Q., Yang, Z., Zhao, L., Yang, C., Gao, H. Tags: Research Articles Source Type: research
Mechanisms of lipid droplet biogenesis
Lipid droplets (LDs) are organelles that compartmentalize nonbilayer-forming lipids in the aqueous cytoplasm of cells. They are ubiquitous in most organisms, including in animals, protists, plants and microorganisms. In eukaryotes, LDs are believed to be derived by a budding and scission process from the surface of the endoplasmic reticulum, and this occurs concomitantly with the accumulation of neutral lipids, most often triacylglycerols and steryl esters. Overall, the mechanisms underlying LD biogenesis are difficult to generalize, in part because of the involvement of different sets of both evolutionarily conserved and ...
Source: Biochemical Journal - July 8, 2019 Category: Biochemistry Authors: Chapman, K. D., Aziz, M., Dyer, J. M., Mullen, R. T. Tags: Review Articles Source Type: research
Correction: Ezrin-anchored PKA phosphorylates serine 369 and 373 on connexin 43 to enhance gap junction assembly, communication, and cell fusion
(Source: Biochemical Journal)
Source: Biochemical Journal - July 1, 2019 Category: Biochemistry Authors: Dukic, A. R., Gerbaud, P., Guibourdenche, J., Thiede, B., Tasken, K., Pidoux, G. Tags: Correction Source Type: research
Nitration-induced ubiquitination and degradation control quality of ERK1
The mitogen-activated protein kinase ERK1/2 (ERKs, extracellular-regulated protein kinases) plays important roles in a wide spectrum of cellular processes and have been implicated in many disease states. The spatiotemporal regulation of ERK activity has been extensively studied. However, scarce information has been available regarding the quality control of the kinases to scavenge malfunctioning ERKs. Using site-specific mutagenesis and mass spectrometry, we found that the disruption of the conserved H-bond between Y210 and E237 of ERK1 through point mutation at or naturally occurring nitration on Y210 initiates a quality ...
Source: Biochemical Journal - July 1, 2019 Category: Biochemistry Authors: Zhang, Y., Huang, X., Wang, J., Wang, X., Liu, X., Chen, Y., Xu, W., Wang, Y. Tags: Research Articles Source Type: research
The search for candidate genes associated with natural variation of grain Zn accumulation in barley
Combating hidden hunger through molecular breeding of nutritionally enriched crops requires a better understanding of micronutrient accumulation. We studied natural variation in grain micronutrient accumulation in barley (Hordeum vulgare L.) and searched for candidate genes by assessing marker-trait associations (MTAs) and by analyzing transcriptional differences between low and high zinc (Zn) accumulating cultivars during grain filling. A collection of 180 barley lines was grown in three different environments. Our results show a pronounced variation in Zn accumulation, which was under strong genotype influence across dif...
Source: Biochemical Journal - July 1, 2019 Category: Biochemistry Authors: Detterbeck, A., Nagel, M., Rensch, S., Weber, M., Börner, A., Persson, D. P., Schjoerring, J. K., Christov, V., Clemens, S. Tags: Research Articles Source Type: research
The ChlD subunit links the motor and porphyrin binding subunits of magnesium chelatase
Magnesium chelatase initiates chlorophyll biosynthesis, catalysing the MgATP2–-dependent insertion of a Mg2+ ion into protoporphyrin IX. The catalytic core of this large enzyme complex consists of three subunits: Bch/ChlI, Bch/ChlD and Bch/ChlH (in bacteriochlorophyll and chlorophyll producing species, respectively). The D and I subunits are members of the AAA+ (ATPases associated with various cellular activities) superfamily of enzymes, and they form a complex that binds to H, the site of metal ion insertion. In order to investigate the physical coupling between ChlID and ChlH in vivo and in vitro, ChlD was FLAG-tag...
Source: Biochemical Journal - July 1, 2019 Category: Biochemistry Authors: Farmer, D. A., Brindley, A. A., Hitchcock, A., Jackson, P. J., Johnson, B., Dickman, M. J., Hunter, C. N., Reid, J. D., Adams, N. B. P. Tags: Research Articles Source Type: research
The glutathione degrading enzyme, Chac1, is required for calcium signaling in developing zebrafish: redox as an upstream activator of calcium
Calcium signaling is essential for embryonic development but the signals upstream of calcium are only partially understood. Here, we investigate the role of the intracellular glutathione redox potential in calcium signaling using the Chac1 protein of zebrafish. A member of the -glutamylcyclotransferase family of enzymes, the zebrafish Chac1 is a glutathione-degrading enzyme that acts only on reduced glutathione. The zebrafish chac1 expression was seen early in development, and in the latter stages, in the developing muscles, brain and heart. The chac1 knockdown was embryonic lethal, and the developmental defects were seen ...
Source: Biochemical Journal - July 1, 2019 Category: Biochemistry Authors: Yadav, S., Chawla, B., Khursheed, M. A., Ramachandran, R., Bachhawat, A. K. Tags: Research Articles Source Type: research
Chemical synthesis and characterization of a new quinazolinedione competitive antagonist for strigolactone receptors with an unexpected binding mode
Strigolactones (SLs) are multifunctional plant hormones regulating essential physiological processes affecting growth and development. In vascular plants, SLs are recognized by α/β hydrolase-fold proteins from the D14/DAD2 (Dwarf14/Decreased Apical Dominance 2) family in the initial step of the signaling pathway. We have previously discovered that N-phenylanthranilic acid derivatives (e.g. tolfenamic acid) are potent antagonists of SL receptors, prompting us to design quinazolinone and quinazolinedione derivatives (QADs and QADDs, respectively) as second-generation antagonists. Initial in silico docking studies ...
Source: Biochemical Journal - June 27, 2019 Category: Biochemistry Authors: Hamiaux, C., Larsen, L., Lee, H. W., Luo, Z., Sharma, P., Hawkins, B. C., Perry, N. B., Snowden, K. C. Tags: Research Articles Source Type: research
Specific keratinase derived designer peptides potently inhibit A{beta} aggregation resulting in reduced neuronal toxicity and apoptosis
Compelling evidence implicates self-assembly of amyloid-β (Aβ1–42) peptides into soluble oligomers and fibrils as a major underlying event in Alzheimer's disease (AD) pathogenesis. Herein, we employed amyloid-degrading keratinase (kerA) enzyme as a key Aβ1–42-binding scaffold to identify five keratinase-guided peptides (KgPs) capable of interacting with and altering amyloidogenic conversion of Aβ1–42. The KgPs showed micromolar affinities with Aβ1–42 and abolished its sigmoidal amyloidogenic transition, resulting in abrogation of fibrillogenesis. Comprehensive assessment usi...
Source: Biochemical Journal - June 27, 2019 Category: Biochemistry Authors: Rajput, R., G L, B., Srivastava, A., Wahi, D., Shrivastava, N., Kundu, B., Grover, A. Tags: Research Articles Source Type: research
Mechanism of nitrite-dependent NO synthesis by human sulfite oxidase
In addition to nitric oxide (NO) synthases, molybdenum-dependent enzymes have been reported to reduce nitrite to produce NO. Here, we report the stoichiometric reduction in nitrite to NO by human sulfite oxidase (SO), a mitochondrial intermembrane space enzyme primarily involved in cysteine catabolism. Kinetic and spectroscopic studies provide evidence for direct nitrite coordination at the molybdenum center followed by an inner shell electron transfer mechanism. In the presence of the physiological electron acceptor cytochrome c, we were able to close the catalytic cycle of sulfite-dependent nitrite reduction thus leading...
Source: Biochemical Journal - June 27, 2019 Category: Biochemistry Authors: Bender, D., Tobias Kaczmarek, A., Niks, D., Hille, R., Schwarz, G. Tags: Research Articles Source Type: research
The histidine-rich loop in the extracellular domain of ZIP4 binds zinc and plays a role in zinc transport
The Zrt-/Irt-like protein (ZIP) family mediates zinc influx from extracellular space or intracellular vesicles/organelles, playing a central role in systemic and cellular zinc homeostasis. Out of the 14 family members encoded in human genome, ZIP4 is exclusively responsible for zinc uptake from dietary food and dysfunctional mutations of ZIP4 cause a life-threatening genetic disorder, Acrodermatitis Enteropathica (AE). About half of the missense AE-causing mutations occur within the large N-terminal extracellular domain (ECD), and our previous study has shown that ZIP4–ECD is crucial for optimal zinc uptake but the u...
Source: Biochemical Journal - June 27, 2019 Category: Biochemistry Authors: Zhang, T., Kuliyev, E., Sui, D., Hu, J. Tags: Research Articles Source Type: research
Thioredoxin-like2/2-Cys peroxiredoxin redox cascade acts as oxidative activator of glucose-6-phosphate dehydrogenase in chloroplasts
In this study, we report a novel protein-activation mechanism based on the TrxL2/2CP redox cascade. Glucose-6-phosphate dehydrogenase (G6PDH) catalyzes the first step of the oxidative pentose phosphate pathway (OPPP). Biochemical studies, including redox state determination and measurement of enzyme activity, suggested that the TrxL2/2CP pathway is involved in the oxidative activation of G6PDH. It is thus likely that the TrxL2/2CP redox cascade shifts chloroplast metabolism to night mode by playing a dual role, namely, down-regulation of the Calvin–Benson cycle and up-regulation of OPPP. G6PDH was also directly oxidi...
Source: Biochemical Journal - June 25, 2019 Category: Biochemistry Authors: Yoshida, K., Uchikoshi, E., Hara, S., Hisabori, T. Tags: Research Articles Source Type: research
The {beta}-hairpin region of the cyanobacterial F1-ATPase {gamma}-subunit plays a regulatory role in the enzyme activity
The -subunit of cyanobacterial and chloroplast ATP synthase, the rotary shaft of F1-ATPase, equips a specific insertion region that is only observed in photosynthetic organisms. This region plays a physiologically pivotal role in enzyme regulation, such as in ADP inhibition and redox response. Recently solved crystal structures of the -subunit of F1-ATPase from photosynthetic organisms revealed that the insertion region forms a β-hairpin structure, which is positioned along the central stalk. The structure–function relationship of this specific region was studied by constraining the expected conformational chang...
Source: Biochemical Journal - June 25, 2019 Category: Biochemistry Authors: Akiyama, K., Kondo, K., Inabe, K., Murakami, S., Wakabayashi, K.-i., Hisabori, T. Tags: Research Articles Source Type: research
DEK terminates diapause by activation of quiescent cells in the crustacean Artemia
To cope with harsh environments, the Artemia shrimp produces gastrula embryos in diapause, a state of obligate dormancy, having cellular quiescence and suppressed metabolism. The mechanism behind these cellular events remains largely unknown. Here, we study the regulation of cell quiescence using diapause embryos of Artemia. We found that Artemia DEK (Ar-DEK), a nuclear factor protein, was down-regulated in the quiescent cells of diapause embryos and enriched in the activated cells of post-diapause embryos. Knockdown of Ar-DEK induced the production of diapause embryos whereas the control Artemia released free-swimming nua...
Source: Biochemical Journal - June 25, 2019 Category: Biochemistry Authors: Jia, W.-H., Li, A.-Q., Feng, J.-Y., Ding, Y.-F., Ye, S., Yang, J.-S., Yang, W.-J. Tags: Research Articles Source Type: research
