Cloning and Nucleotide Sequences of Two Genes Involved in Macrolide Antibiotics from Streptomyees thermotolerans the 4 "-O-Acylation of

carrying.,the region conyerted exogenously added tylosin to 4"-O-acyltylosins. Nucleotide sequencing of the regien showed two open readiilg frames (ORFs). Expression assay usi"g deleted plasmids showed that .both OIUTs were essential for optimal expression of the acyltransferase activity. One of them (a(zyBl) was identical with carE reported preyiously as a gene encoding 4"-mycarosyl isoyaleryl-CeA transferase. The