A two-protein component 7 alpha-cephem-methoxylase encoded by two genes of the cephamycin C cluster converts cephalosporin C to 7-methoxycephalosporin C.
Two genes, cmcI and cmcJ, corresponding to open reading frames 7 and 8 (ORF7 and ORF8) of the cephamycin C cluster of Nocardia lactamdurans encode enzymes that convert cephalosporin C to 7-methoxycephalosporin C. Proteins P7 and P8 (the products of ORF7 and ORF8 expressed in Streptomyces lividans) introduce the methoxyl group at C-7 of the cephem nucleus. Efficient hydroxylation at C-7 and transfer of the methyl group from S-adenosylmethionine require both proteins P7 and P8, although P7 alone shows weak C-7 hydroxylase activity and strong cephalosporin-dependent NADH oxidase activity. Both P7 and P8 appear to be synthesized in a coordinated form by translational coupling of cmcI and cmcJ. Protein P7 contains domains that correspond to conserved sequences in cholesterol 7 alpha-monooxygenases and to the active center of O-methyltransferases by comparison with the crystal structure of catechol-O-methyltransferase. Protein P8 may act as a coupling protein for efficient hydroxylation at C-7 in a form similar to that of the two-component system of Pseudomonas putida p-hydroxyphenylacetate-3-hydroxylase.
Coque
J J
JJ
Department of Ecology, Genetics and Microbiology, Faculty of Biology, University of León, Spain.
Enguita
F J
FJ
Martín
J F
JF
Liras
P
P
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002511:Cephalosporins / Q000096:biosynthesis* / Q000378:metabolism; D002513:Cephamycins / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics* / Q000378:metabolism*; D005810:Multigene Family; D009615:Nocardia / Q000235:genetics* / Q000378:metabolism*; D016366:Open Reading Frames; D015183:Restriction Mapping
D001426:Bacterial Proteins; D002511:Cephalosporins; D002513:Cephamycins; D004269:DNA, Bacterial; D009097:Multienzyme Complexes; C093122:7-alpha-cephem-methoxylase; C025163:cephalosporin C; C024926:7-methoxycephalosporin C; D006899:Mixed Function Oxygenases; D008780:Methyltransferases; C024925:cephamycin C