Biochemical characterization of a malonyl-specific acyltransferase domain of FK506 biosynthetic polyketide synthase.

Acyltransferases (ATs) play an essential role in the polyketide biosynthesis through transferring acyl units into acyl carrier proteins (ACPs) via a self-acylation reaction and a transacylation reaction. Here we used AT10FkbA of FK506 biosynthetic polyketide synthase (PKS) from Streptomyces tsukubaensis YN06 as a model to study the specificity of ATs for acyl units. Our results show that AT10FkbA can form both malonyl-O-AT10FkbA and methylmalonyl-O-AT10FkbA in the self-acylation reaction, however, only malonyl-O-AT10FkbA but not methylmalonyl-O-AT10FkbA can transfer the acyl unit into ACPs in the transacylation reaction.

Characterization of type II thioesterases involved in natamycin biosynthesis in Streptomyces chattanoogensis L10.

The known functions of type II thioesterases (TEIIs) in type I polyketide synthases (PKSs) include selecting of starter acyl units, removal of aberrant extender acyl units, releasing of final products, and dehydration of polyketide intermediates. In this study, we characterized two TEIIs (ScnI and PKSIaTEII) from Streptomyces chattanoogensis L10. Deletion of scnI in S.

Characterization and evolutionary implications of the triad Asp-Xxx-Glu in group II phosphopantetheinyl transferases.

Phosphopantetheinyl transferases (PPTases), which play an essential role in both primary and secondary metabolism, are magnesium binding enzymes. In this study, we characterized the magnesium binding residues of all known group II PPTases by biochemical and evolutionary analysis. Our results suggested that group II PPTases could be classified into two subgroups, two-magnesium-binding-residue-PPTases containing the triad Asp-Xxx-Glu and three-magnesium-binding-residue-PPTases containing the triad Asp-Glu-Glu.

Improvement of natamycin production by engineering of phosphopantetheinyl transferases in Streptomyces chattanoogensis L10.

Phosphopantetheinyl transferases (PPTases) are essential to the activities of type I/II polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs) through converting acyl carrier proteins (ACPs) in PKSs and peptidyl carrier proteins (PCPs) in NRPSs from inactive apo-forms into active holo-forms, leading to biosynthesis of polyketides and nonribosomal peptides. The industrial natamycin (NTM) producer, Streptomyces chattanoogensis L10, contains two PPTases (SchPPT and SchACPS) and five PKSs. Biochemical characterization of these two PPTases shows that SchPPT catalyzes the phosphopantetheinylation of ACPs in both type I PKSs and type II PKSs, SchACPS catalyzes the phosphopantetheinylation of ACPs in type II PKSs and fatty acid synthases (FASs), and the specificity of SchPPT is possibly controlled by its C terminus.