GLYCOSYLATION OF MACROLIDE ANTIBIOTICS IN EXTRACTS OF STREPTOMYCES-LIVIDANS

Inducible resistance to macrolide antibiotics in Streptomyces lividans involves MGT, a macrolide glycosyl transferase that utilizes UDP-glucose as cofactor. Substrates for MGT include macrolides with 12-, 14-, 15-, or 16-atom cyclic polyketide lactones (as in methymycin, erythromycin, azithromycin, or tylosin, respectively), although spiramycin and carbomycin are not apparently modified. The enzyme is specific for the 2'-OH group of saccharidic moieties attached to C-5 of the 16-atom lactone ring (corresponding to C-5 or C-3 in 14- or 12-atom lactones, respectively).