Biosynthetic Mechanisms of C-P Bond Formation of Bialaphos.

Abstract

Bialaphos (BA) is a tripeptide produced by Streptomyces hygroscopicus SF-1293 and is characterized by the presence of a unique C-P-C bond. Through the biosynthetic studies on BA we have revealed the involvement of three enzymes catalyzing different C-P bond formation mechanisms. Two of them, phosphoenolpyruvate phosphomutase (PEP phosphomutase) and carboxyphosphonoenolpyruvate phosphonomutase (CPEP phosphonomutase), have been purified and characterized to catalyze the reactions of a similar type, i.e., intramolecular rearrangements of phosphate esters to form a C-P bond. On the other hand, the remaining one catalyzes P-methylation of phosphinic acid derivatives. In order to reveal these enzymatic properties in more detail, the corresponding genes were identified in the biosynthetic cluster of BA and then expressed in S. lividans. Introduction of PEP phosphomutase or CPEP phosphonomutase gene into S. lividans using pIJ680 resulted in efficient expression of the corresponding enzymes. On the other hand, the P-methylation enzyme was only expressed in S. lividans when the gene was under control of a thiostrepton-inducible strong promoter of pAK114.