Deacetoxycephalosporin C synthase isozymes exhibit diverse catalytic activity and substrate specificity.
The biosynthesis of cephalosporins involving a thiozolidine ring expansion is catalyzed by deacetoxycephalosporin C synthase (DAOCS). In this study, three DAOCS isozymes were cloned and expressed as active enzymes together with Streptomyces jumonjinensis DAOCS that was newly isolated and partially characterized. The enzymes showed excellent substrate conversion for penicillin G, phenethicillin, ampicillin and carbenicillin, but they were less effective in the ring expansion of penicillin V, amoxicillin and metampicillin. Streptomyces clavuligerus DAOCS was the most active among the recombinant enzymes. The results also showed that truncation of 20 amino acids at the C-terminus of the Acremonium chrysogenum deacetoxy/deacetylcephalosporin C synthase polypeptide did not affect penicillin ring expansion.
Chin
Hong Soon
HS
Department of Microbiology, Faculty of Medicine, National University of Singapore, 5 Science Drive 2, 117597, Singapore, Singapore.
Sim
Janet
J
Seah
Keng Ing
KI
Sim
Tiow Suan
TS
D000595:Amino Acid Sequence; D002384:Catalysis; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D019751:Intramolecular Transferases / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D008958:Models, Molecular; D046915:Penicillin-Binding Proteins; D010406:Penicillins / Q000378:metabolism; D013302:Streptomyces / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D013379:Substrate Specificity
D007527:Isoenzymes; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D019751:Intramolecular Transferases; C038371:deacetoxycephalosporin C synthetase