Lm. Quiros et al., 2 GLYCOSYLTRANSFERASES AND A GLYCOSIDASE ARE INVOLVED IN OLEANDOMYCINMODIFICATION DURING ITS BIOSYNTHESIS BY STREPTOMYCES-ANTIBIOTICUS, Molecular microbiology, 28(6), 1998, pp. 1177-1185
A 5.2 kb region from the oleandomycin gene cluster in Streptomyces ant
ibioticus located between the oleandomycin polyketide synthase gene an
d sugar biosynthetic genes was cloned. Sequence analysis revealed the
presence of three open reading frames (designated olel, oleN2 and oleR
). The olel gene product resembled glycosyltransferases involved in ma
crolide inactivation including the oleD product, a previously describe
d glycosyltransferase from S. antibioticus. The oleN2 gene product sho
wed similarities with different aminotransferases involved in the bios
ynthesis of 6-deoxyhexoses. The oleR gene product was similar to sever
al glucosidases from different origins. The olel, oleR and oleD genes
were expressed in Streptomyces lividans. Olel and OleD intracellular p
roteins were partially purified by affinity chromatography in an UDP-g
lucuronic acid agarose column and OleR was detected as a major band fr
om the culture supernatant. Olel and OleD showed oleandomycin glycosyl
ating activity but they differ in the pattern of substrate specificity
: Olel being much more specific for oleandomycin. OleR showed glycosid
ase activity converting glycosylated oleandomycin into active oleandom
ycin. A model is proposed integrating these and previously reported re
sults for intracellular inactivation, secretion and extracellular reac
tivation of oleandomycin.