Identification and Expression of Genes Involved in Biosynthesis of l -Oleandrose and Its Intermediate l -Olivose in the Oleandomycin Producer Streptomyces antibioticus

Abstract

ABSTRACT A 9.8-kb DNA region from the oleandomycin gene cluster in Streptomyces antibioticus was cloned. Sequence analysis revealed the presence of 8 open reading frames encoding different enzyme activities involved in the biosynthesis of one of the two 2,6-deoxysugars attached to the oleandomycin aglycone: l -oleandrose (the oleW , oleV , oleL , and oleU genes) and d -desosamine (the oleNI and oleT genes), or of both (the oleS and oleE genes). A Streptomyces albus strain harboring the oleG2 glycosyltransferase gene integrated into the chromosome was constructed. This strain was transformed with two different plasmid constructs (pOLV and pOLE) containing a set of genes proposed to be required for the biosynthesis of dTDP- l -olivose and dTDP- l -oleandrose, respectively. Incubation of these recombinant strains with the erythromycin aglycon (erythronolide B) gave rise to two new glycosylated compounds, identified as l -3- O -olivosyl- and l -3- O -oleandrosyl-erythronolide B, indicating that pOLV and pOLE encode all enzyme activities required for the biosynthesis of these two 2,6-dideoxysugars. A pathway is proposed for the biosynthesis of these two deoxysugars in S. antibioticus .