Condensation-Incompetent Ketosynthase Inhibits trans-Acyltransferase Activity.

Nonelongating modules with condensation-incompetent ketosynthase (KS) are frequently found in many trans-acyltransferase polyketide synthases ( trans-AT PKS). KS catalyzes translocation of carbon chain without decarboxylative condensation. Unlike typical elongating modules where malonylation of acyl carrier protein (ACP) precedes elongation, the malonylation of ACP downstream of KS is assumed to be prevented.