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Publication Abstract from PubMed

Numerous cytochrome P450s are involved in secondary metabolite biosynthesis. The biosynthetic gene cluster for reveromycin A (RM-A), which is a promising lead compound with anti-osteoclastic activity, also includes a P450 gene, revI. To understand the roles of P450revI, we comprehensively characterized the enzyme by genetic, kinetic, and structural studies. The revI gene disruptants (DeltarevI) resulted in accumulation of reveromycin T (RM-T), and revI gene complementation restored RM-A production, indicating that the physiological substrate of P450revI is RM-T. Indeed, the purified P450revI catalyzed the C18-hydroxylation of RM-T more efficiently than the other RM derivatives tested. Moreover, the 1.4-A resolution co-crystal structure of P450revI with RM-T revealed that the substrate binds the enzyme with a folded compact conformation for C18-hydroxylation. To address the structure-enzyme activity relationship, site-directed mutagenesis was performed in P450revI. Arg190Ala and Arg81Ala mutations, which abolished salt bridge formation with C1 and C24 carboxyl groups of RM-T, respectively, resulted in significant loss of enzyme activity. The interaction between Arg190 and the C1 carboxyl group of RM-T elucidated why P450revI was unable to catalyze both RM-T 1-methyl ester and RM-T 1-ethyl ester. Moreover, the accumulation of RM-T in DeltarevI mutants enabled us to characterize its biological activity. Our results show that RM-T had stronger anticancer activity and isoleucyl-tRNA synthetase inhibition than RM-A. However, RM-T showed much less anti-osteoclastic activity than RM-A, indicating that hemisuccinate moiety is important for the activity. Structure-based P450revI engineering for novel hydroxylation and subsequent hemisuccinylation will help facilitate the development of RM-derivatives with anti-osteoclast activity.

Structure-Function Analyses of Cytochrome P450revI Involved in Reveromycin A Biosynthesis and Evaluation of the Biological Activity of Its Substrate, Reveromycin T.,Takahashi S, Nagano S, Nogawa T, Kanoh N, Uramoto M, Kawatani M, Shimizu T, Miyazawa T, Shiro Y, Osada H J Biol Chem. 2014 Sep 25. pii: jbc.M114.598391. PMID:25258320^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.