Identification of a cysteine involved in the interaction between carbon monoxide dehydrogenase and corrinoid/Fe-S protein from Clostridium thermoaceticum.
In Clostridium thermoaceticum, the synthesis of acetyl-CoA from methyl tetrahydrofolate occurs via a series of enzymatic reactions involving methyl transferase, corrinoid/Fe-S protein (corrinoid), carbon monoxide dehydrogenase (CODH) and ferredoxin. We have investigated the possibility of one or more of these proteins existing as multi-enzyme complexes in vivo with higher catalytic activity. A protein complex consisting of CODH and corrinoid was isolated from the cell-free extracts of Clostridium thermoaceticum. The acetyl-CoA synthesis was found to be approximately 1.8-fold higher with the complex than that observed with the isolated protein components. HPLC gel filtration analyses of the native and DTE reduced complex suggested that the CODH:corrinoid complex is held together primarily by an inter disulfide bond. By differential labeling of thiols with [14C]N-ethylmaleimide it was found that Cys-506 of the alpha subunit of CODH was involved in the disulfide linkage with the corrinoid of the complex.
Shanmugasundaram
T
T
Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106.
Sundaresh
C S
CS
Kumar
G K
GK
D000105:Acetyl Coenzyme A / Q000096:biosynthesis; D000445:Aldehyde Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D003013:Clostridium / Q000201:enzymology*; D045728:Corrinoids; D003545:Cysteine; D004220:Disulfides / Q000378:metabolism; D004226:Dithioerythritol; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism; D014805:Vitamin B 12 / Q000378:metabolism*
D045728:Corrinoids; D004220:Disulfides; D007506:Iron-Sulfur Proteins; D009097:Multienzyme Complexes; D004226:Dithioerythritol; D000105:Acetyl Coenzyme A; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase; D003545:Cysteine; D014805:Vitamin B 12