OA-6129 A

A933 acylase, which is involved in exchange of the pantothenyl substituent of OA-6129 carbapenems with acetyl CoA, was characterized as an L-amino acid acylase with a molecular weight of 100,000 (+/- 8,000) and a pI value of 5.1. The highest L-amino acid acylase activity of A933 acylase was observed at 37 degrees C and pH 7 approximately 7.5 for N-chloroacetyl-L-phenylalanine. Unlike other amino acid acylases, A933 acylase was severely inhibited by cobalt ions and p-chloromercuribenzoate. The acylase also showed peptidase activity with some di- and tripeptides. A protein fraction with A933 L-amino acid acylase activity from blocked mutant 1501 lacked OA-6129A-depantothenylating activity.

Streptomyces fulvoviridis A933 17M9 1501 is an A933 acylase-defective mutant derived from S. fulvoviridis A933 17M9 and thus produces the OA-6129 group of carbapenems and carbapenams. By further mutation of mutant 1501, 4 types of mutants (OA-6129 A + B1 + B2 producers; OA-6129 A + B2 producers; an OA-6129 A producer; non-producers) were obtained. The second type of mutant strains 4N 3607, 5NA 3949-40 and 5NE 252 proved useful for the fermentative production of carbapenem OA-6129 B2. These results of mutagenesis demonstrated that the sequence of carbapenem bioconversion in the horizontal route was hydroxylation at C-8----isomerization at C-6----sulfation at C-8 hydroxyl.

The OA-6129 group of carbapenem antibiotics were phosphorylated with ATP by Brevibacterium ammoniagenes at the primary hydroxyl group of the C-3 pantetheinyl side chain. The phosphorylation resulted in the reduced antimicrobial activity against some Gram-positive bacteria, and the improved activity against some Gram-negative microbes. The increased resistance of the OA-6129 carbapenems due to phosphorylation was significant to mouse renal dehydropeptidase and moderate to the human enzyme. OA-6129A and B2 phosphates were found to be unsusceptible to A933 acylase, while OA-6129A and B2 were depantothenylated.