This research application focuses on mechanistic studies of three key enzymes in the Wood-Ljungdahl pathway: CO dehydrogenase/acetyl-CoA synthase (CODH/ACS), methyltransferase (MeTr), and the corrinoid iron-sulfur protein (CFeSP). Studies on this system have enriched the areas of microbiology, biochemistry, and metallobiochemistry in revealing the structures of macromolecular channels and previously unknown metal clusters. These studies are providing insight into how these proteins use bioorganometallic intermediates in catalyzing group transfer reactions and C-C and C-S bond formation and cleavage allowing organisms to assimilate carbon dioxide and the toxic gas, CO. This system serves as a paradigm for understanding bioinorganic chemical principles, complex protein-protein interactions, and how proteins coordinate redox reactions with chemical catalysis. The major focus of this application is on multidisciplinary structure-functions studies of the three major classes of Ni-CODHs: the monofunctional CODH, the bifunctional CODH/ACS from acetogenic bacteria, and the bifunctional CODH/ACS (also called acetyl-CoA decarbonylase synthase, ACDS) from aceticlastic methanogens. Because these enzymes play different physiological roles, they are hypothesized to exhibit correspondingly disparate catalytic properties, including different mechanisms of substrate channeling, catalytic biases for CO oxidation/carbon dioxide reduction, and electrochemical properties. The proton transfer network including the acid-base catalyst(s), conserved among all CODH classes, will be further investigated. The early intermediate(s) in the CODH mechanism will be trapped and characterized. The internal electron transfer reaction in the ACS mechanism will be characterized. We will further investigate how the CO channel in CODH/ACS meters the supply of and demand for CO and investigate how the CODH and ACS sites in CODH/ACS are coordinated. We also will determine the crystal structure of the CFeSP- MeTr complex and investigate the proposed role of a major conformational change in the reaction of MeTr with the CFeSP. Studies on PFOR will test a kinetic coupling hypothesis, including identification of a proposed radical species formed by reaction of CoA with the hydroxyethyl-TPP radical.

Public Health Relevance

We are studying the key enzymes in a pathway by which anaerobic microbes assimilate carbon dioxide and carbon monoxide. These studies involve the elucidating new roles of metal ions in biology (metal-carbon bonds, new heterometallic clusters, and nucleophilic metal ions), characterizing novel substrate-derived radical intermediates, and describing channels for gaseous substrates within an enzyme.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM039451-25
Application #
8019573
Study Section
Special Emphasis Panel (ZRG1-BST-S (90))
Program Officer
Hagan, Ann A
Project Start
1991-08-01
Project End
2012-01-31
Budget Start
2011-02-01
Budget End
2012-01-31
Support Year
25
Fiscal Year
2011
Total Cost
$313,253
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Biochemistry
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Gibson, Marcus I; Chen, Percival Yang-Ting; Johnson, Aileen C et al. (2016) One-carbon chemistry of oxalate oxidoreductase captured by X-ray crystallography. Proc Natl Acad Sci U S A 113:320-5
Wang, Vincent C-C; Islam, Shams T A; Can, Mehmet et al. (2015) Investigations by Protein Film Electrochemistry of Alternative Reactions of Nickel-Containing Carbon Monoxide Dehydrogenase. J Phys Chem B 119:13690-7
Gibson, Marcus I; Brignole, Edward J; Pierce, Elizabeth et al. (2015) The Structure of an Oxalate Oxidoreductase Provides Insight into Microbial 2-Oxoacid Metabolism. Biochemistry 54:4112-20
Wang, Vincent C-C; Can, Mehmet; Pierce, Elizabeth et al. (2013) A unified electrocatalytic description of the action of inhibitors of nickel carbon monoxide dehydrogenase. J Am Chem Soc 135:2198-206
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Chaudhary, Yatendra S; Woolerton, Thomas W; Allen, Christopher S et al. (2012) Visible light-driven CO2 reduction by enzyme coupled CdS nanocrystals. Chem Commun (Camb) 48:58-60
Ragsdale, Stephen W; Yi, Li; Bender, Güneş et al. (2012) Redox, haem and CO in enzymatic catalysis and regulation. Biochem Soc Trans 40:501-7
Ando, Nozomi; Kung, Yan; Can, Mehmet et al. (2012) Transient B12-dependent methyltransferase complexes revealed by small-angle X-ray scattering. J Am Chem Soc 134:17945-54
Kung, Yan; Ando, Nozomi; Doukov, Tzanko I et al. (2012) Visualizing molecular juggling within a B12-dependent methyltransferase complex. Nature 484:265-9

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