Patent ID: 7148045

Claim:
A type I polyketide synthase which produces a polyketide and which comprises a loading module and a plurality of extension modules, wherein: a) said loading module loads an optionally substituted malonyl and then effects decarboxylation of the loaded moiety to provide a corresponding optionally substituted acetyl moiety for transfer to the first of said extension modules; and b) said loading module is of the form: (engineered-KSq)-(AT)-(ACP), wherein: i) ACP is an acyl carrier protein domain; ii) AT is an acyltransferase domain which loads an optionally substituted malonyl; and iii) engineered-KSq is a ketosynthase (KS) domain which effects decarboxylation of a loaded optionally substituted malonyl, wherein said engineered-KSq domain is obtained by replacing the active site cysteine of a KS domain of an extension module with a glutamine; wherein the polyketide produced by the polyketide synthase is other than a 14-membered macrolide having a 13-methyl group due to incorporation of an unsubstituted acetate starter.