Role of glycosylation and deglycosylation in biosynthesis of and resistance to oleandomycin in the producer organism, Streptomyces antibioticus

Abstract

Cell extracts of Streptomyces antibioticus, an oleandomycin producer, can inactivate oleandomycin in the presence of UDP-glucose. The inactivation can be detected through the loss of biological activity or by alteration in the chromatographic mobility of the antibiotic. This enzyme activity also inactivates other macrolides (rosaramicin, methymycin, and lankamycin) which contain a free 2'-OH group in a monosaccharide linked to the lactone ring (with the exception of erythromycin), but not those which contain a disaccharide (tylosin, spiramycin, carbomycin, josamycin, niddamycin, and relomycin). Interestingly, the culture supernatant contains another enzyme activity capable of reactivating the glycosylated oleandomycin and regenerating the biological activity through the release of a glucose molecule. It is proposed that these two enzyme activities could be an integral part of the oleandomycin biosynthetic pathway.

Dispensable ribosomal resistance to spiramycin conferred by srmA in the spiramycin producer Streptomyces ambofaciens The EMBL/GenBank accession number for the nucleotide sequence described in this paper is AJ223970.

“…, including S. ambofaciens. Macrolide inactivation can be due to different modifications, for instance phosphorylation (Marshall et al, 1989 ;O'Hara et al, 1989), glycosylation (Kuo et al, 1989 ;Cundliffe, 1992 ;Vilches et al, 1992) or esterification of the lactone ring (Ounissi & Courvalin, 1985 ;Arthur et al, 1986).…”

Purification and characterization of an extracellular enzyme from Streptomyces antibioticus that converts inactive glycosylated oleandomycin into the active antibiotic

“…Nevertheless, a glycosylated oleandomycin derivative has been detected in the fermentation broths of S. antibioticus (Celmer et al, 1985) and there is evidence that oleandomycin could be synthesized and secreted as an inactive glycosylated derivative (Vilches et al, 1992). Here, we present the purification and characterization of this enzyme activity from the S. antibioticus culture supernatants which is able to convert the inactive glycosylated oleandomycin into an active molecule.…”

“…This points to the existence of a second enzymic activity (either extracellular or membrane-located), capable of generating the final active antibiotic molecule. Such an enzyme activity has been found in the oleandomycin producer, Streptomyces antibioticus (Vilches et al, 1992). Oleandomycin ( Fig.…”

“…At first sight, intracellular inactivation of the produced antibiotic does not seem to be a logical survival mechanism for an organism that is trying to synthesize an active antibiotic. In some cases, experimental evidence supporting a role for these enzymes in antibiotic biosynthesis has been reported (Miller and Walker, 1969;Walker and Skorvaga, 1973;Satoh et al, 1975;Vara et al, 1985;Murakami et al, 1986;Vilches et al, 1992). Nevertheless, since the final intracellular product of these pathways is an inactive antibiotic, the molecule must recover its antimicrobial functionality during or after its secretion.…”

“…1) is a 14-membered macrolide antibiotic which is structurally related to erythromycin and inhibits protein synthesis by interacting with the 50s ribosomal subunit. The producer organism possesses oleandomycin-sensitive ribosomes throughout the cell (Vilches et al, 1992) as potential site for glycosylation.…”