Molecular basis for short-chain thioester hydrolysis by acyl hydrolase domains in -acyltransferase polyketide synthases.

Polyketide synthases (PKSs) are multi-domain enzymatic assembly lines that biosynthesise a wide selection of bioactive natural products from simple building blocks. In contrast to their -acyltransferase (AT) counterparts, -AT PKSs rely on stand-alone AT domains to load extender units onto acyl carrier protein (ACP) domains embedded in the core PKS machinery. -AT PKS gene clusters also encode acyl hydrolase (AH) domains, which are predicted to share the overall fold of AT domains, but hydrolyse aberrant acyl chains from ACP domains, thus ensuring efficient polyketide biosynthesis.

Elucidating the molecular programming of a nonlinear non-ribosomal peptide synthetase responsible for fungal siderophore biosynthesis.

Siderophores belonging to the ferrichrome family are essential for the viability of fungal species and play a key role for virulence of numerous pathogenic fungi. Despite their biological significance, our understanding of how these iron-chelating cyclic hexapeptides are assembled by non-ribosomal peptide synthetase (NRPS) enzymes remains poorly understood, primarily due to the nonlinearity exhibited by the domain architecture. Herein, we report the biochemical characterization of the SidC NRPS, responsible for construction of the intracellular siderophore ferricrocin.

Molecular basis for acyl carrier protein-ketoreductase interaction in -acyltransferase polyketide synthases.

The biosynthesis of polyketides by type I modular polyketide synthases (PKS) relies on co-ordinated interactions between acyl carrier protein (ACP) domains and catalytic domains within the megasynthase. Despite the importance of these interactions, and their implications for biosynthetic engineering efforts, they remain poorly understood. Here, we report the molecular details of the interaction interface between an ACP domain and a ketoreductase (KR) domain from a -acyltransferase (-AT) PKS.

Clicking into Place: Interfacing Terminal Alkyne Biosynthesis with Polyketide Synthases.

Engineering polyketide biosynthesis to enable the production of diverse chemical structures is a major challenge at present. Utilising an established biosynthetic cassette for terminal alkyne production, Porterfield et al. applied docking domain and site-directed mutagenesis approaches to interface these enzymes with modular polyketide synthase (PKS) enzymes, yielding products with a bio-orthogonal handle.