ANALYSIS OF 4 TYLOSIN BIOSYNTHETIC GENES FROM THE TYLLM REGION OF THESTREPTOMYCES-FRADIAE GENOME

The tylLM region of the tylosin biosynthetic gene cluster of Streptomy ces fradiae contains four open reading frames (orfs1-4*). The functio n of the orf1 product is not known. The product of orf2* (tylM2) is t he glycosyltransferase that adds mycaminose to the 5-hydroxyl group of tylactone, the polyketide aglycone of tylosin (Ty). A methyltransfera se, responsible for 3-N-methylation during mycaminose production, is e ncoded by orf3 (tylM1). The product of orf4* (ccr) is crotonyl-CoA re ductase, which converts acetoacetyl-CoA to butyryl-CoA for use as a 4C extender unit during tylactone production.