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Journal article
Inhibition of Escherichia coli CTP Synthetase by NADH and Other Nicotinamides and Their Mutual Interactions with CTP and GTP
Biochemistry (Easton), v 55(39), pp 5554-5565
04 Oct 2016
PMID: 27571563
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
CTP synthetases catalyze the last step of pyrimidine biosynthesis and provide the sole de novo source of cytosine-containing nucleotides. As a central regulatory hub, they are regulated by ribonucleotide and enzyme concentration through ATP and UTP substrate availability, CTP product inhibition, GTP allosteric modification, and quaternary structural changes including the formation of CTP-inhibited linear polymers (filaments). Here, we demonstrate that nicotinamide redox cofactors are moderate inhibitors of Escherichia coli CTP synthetase (EcCTPS). NADH and NADPH are the most potent, and the primary inhibitory determinant is the reduced nicotinamide ring. Although nicotinamide inhibition is noncompetitive with substrates, it apparently enhances CTP product feedback inhibition and GTP allosteric regulation. Further, CTP and GTP also enhance each other's effects, consistent with the idea that NADH, CTP, and GTP interact with a common intermediate enzyme state. A filament-blocking mutation that reduces CTP inhibitory effects also reduced inhibition by GTP but not NADH. Protein-concentration effects on GTP inhibition suggest that, like CTP, GTP preferentially binds to the filament. All three compounds display nearly linear dose-dependent inhibition, indicating a complex pattern of cooperative interactions between binding sites. The apparent synergy between inhibitors, in consideration with physiological nucleotide concentrations, points to metabolically relevant inhibition by nicotinamides, and implicates cellular redox state as a regulator of pyrimidine biosynthesis.
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Details
- Title
- Inhibition of Escherichia coli CTP Synthetase by NADH and Other Nicotinamides and Their Mutual Interactions with CTP and GTP
- Creators
- Chris Habrian - University of California, DavisAdithi Chandrasekhara - University of California, DavisBita Shahrvini - University of California, DavisBrian Hua - Massachusetts Institute of TechnologyJason Lee - University of California, DavisRoger Jesinghaus - University of California, DavisRachael Barry - Princeton UniversityZemer Gitai - Princeton UniversityJustin Kollman - University of WashingtonEnoch P Baldwin - University of California, DavisJinwook Lee - Decision Sciences (and Management Information Systems)
- Publication Details
- Biochemistry (Easton), v 55(39), pp 5554-5565
- Publisher
- American Chemical Society; Washington, DC
- Grant note
- R01 GM063109 / NIGMS NIH HHS R01 GM097073 / NIGMS NIH HHS K12 GM068524 / NIGMS NIH HHS R01 GM107384 / NIGMS NIH HHS
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Decision Sciences (and Management Information Systems)
- Web of Science ID
- WOS:000384842100006
- Scopus ID
- 2-s2.0-84990059446
- Other Identifier
- 991019173566904721
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- Collaboration types
- Industry collaboration
- Domestic collaboration
- Web of Science research areas
- Biochemistry & Molecular Biology