Polyketide versatility in the biosynthesis of complex mycobacterial cell wall lipids

Genome sequencing of Mycobacterium tuberculosis (Mtb) has revealed a large number of open reading frames homologous to polyketide synthases (PKSs). Since Mtb is not known to produce secondary metabolites, their presence in the Mtb genome was rather surprising. Research over the last decade has demonstrated that these PKSs are involved in the biosynthesis and assembly of complex lipids. The catalytic as well as mechanistic versatility of PKSs in producing acyl chains of Mtb lipidic metabolites are discussed here. We refer to the literature for most bench-level details, but include protocols for generally useful methods for analyzing the products of mycobacterial PKSs.