Purification and molecular characterization of the electron transfer protein of methanesulfonic acid monooxygenase.
A novel serine pathway methylotroph, strain M2, capable of utilizing methanesulfonic acid (MSA) as a sole source of carbon and energy was investigated. The initial step in the biodegradative pathway of MSA in strain M2 involved an inducible NADH-specific monooxygenase enzyme (MSAMO). Fractionation of MSAMO active cell extracts by ion-exchange chromatography led to the loss of MSAMO activity. Activity was restored by mixing three distinct protein fractions, designated A, B, and C. Further purification to homogeneity of component C indicated that the polypeptide was acidic, with a pI of 3.9, and contained an iron-sulfur center with spectral characteristics similar to those of other proteins containing Rieske [2Fe-2S] centers. The size of the protein subunit and the similarity of the N-terminal sequence to those of ferredoxin components of other oxygenase enzymes have suggested that component C is a specific electron transfer protein of the MSAMO which contains a Rieske [2Fe-2S] cluster. The gene encoding component C of MSAMO was cloned and sequenced, and the predicted protein sequence was compared with those of other Rieske [2Fe-2S]-center-containing ferredoxins. MSAMO appears to be a novel combination of oxygenase elements in which an enzyme related to aromatic-ring dioxygenases attacks a one-carbon (C1) compound via monooxygenation.
Higgins
T P
TP
Department of Biological Sciences, University of Warwick, Coventry, United Kingdom.
De Marco
P
P
Murrell
J C
JC
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004579:Electron Transport; D005288:Ferredoxins / Q000737:chemistry; D006088:Gram-Negative Aerobic Bacteria / Q000201:enzymology* / Q000235:genetics; D008698:Mesylates / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000737:chemistry*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D016415:Sequence Alignment
D005288:Ferredoxins; D008698:Mesylates; C045880:methanesulfonic acid; D006899:Mixed Function Oxygenases; C104883:methanesulfonic acid monooxygenase