An unusual beta-ketoacyl : acyl carrier protein synthase and acyltransferase motifs in TaK, a putative protein required for biosynthesis of the antibiotic TA in Myxococcus xanthus

The antibiotic TA of Myxococcus xanthus is produced by a type-1 polyketide synthase mechanism. Previous Studies have indicated that TA genes are clust ered within a 36-kb region. The chemical structure of TA indicates the need for several post-modification steps. which are introduced to form the fina l bioactive molecule. These include three C-methylations. an O-methylation and a specific hydroxylation, In this study, we describe the genetic analys is of taK, encoding a specific polyketide beta -ketoacyl:acyl carrier prote in synthase, which contains an unusual beta -ketoacyl synthase and acyltran sferase motifs and is likely to be involved in antibiotic TA post-modificat ion. Functional analysis of this beta -ketoacyl:acyl carrier protein syntha se by specific gene disruption suggests that it is essential for the produc tion of an active TA molecule. (C) 2001 Federation of European Microbiologi cal Societies. Published by Elsevier Science B.V. All rights reserved.