Component A of the methyl coenzyme M methylreductase system of Methanobacterium: resolution into four components.
Component A, the oxygen-sensitive protein fraction of the methyl coenzyme M methylreductase system of Methanobacterium thermoautotrophicum, has been stabilized and resolved into three protein fractions and one cofactor that are required to reconstitute component A activity. Component A1 is oxygen-stable and contains hydrogen-dependent deazaflavin (coenzyme F420)-reducing activity. Component A2 is acidic; components A2 and A3 are oxygen sensitive. The specific functions of each component in methyl group reduction are unknown. Resolution of component A revealed a new cofactor requirement of the methylreductase system for FAD. Hydrogen-dependent reduction of methyl coenzyme M to methane and coenzyme M, the terminal step of CO2 reduction by methanogenic bacteria, requires protein components A1, A2, A3, and C in addition to component B, FAD, ATP, and Mg2+.
D001426:Bacterial Proteins / Q000032:analysis; D019605:Euryarchaeota / Q000201:enzymology*; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D046911:Macromolecular Substances; D008623:Mercaptoethanol / Q000031:analogs & derivatives*; D015080:Mesna / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism
D001426:Bacterial Proteins; D046911:Macromolecular Substances; D005182:Flavin-Adenine Dinucleotide; D008623:Mercaptoethanol; D010088:Oxidoreductases; C023895:methyl coenzyme M methylreductase; D015080:Mesna