Biosynthesis of polyketides by -AT polyketide synthases in Burkholderiales.

Widely used as drugs and agrochemicals, polyketides are a family of bioactive natural products, with diverse structures and functions. Polyketides are produced by megaenzymes termed as polyketide synthases (PKSs). PKS biosynthetic pathways are divided into the -AT PKSs and -AT PKSs; a division based mainly on the absence of an acyltransferase (AT) domain in the AT PKS modules. In -AT biosynthesis, the AT activity is contributed via one or several independent proteins, and there are few other characteristics that distinguish -AT PKSs from -AT PKSs, especially in the formation of the β-branch. The -AT PKSs constitute a major PKS pathway, and many are found in species, which are prevalent in the environment and prolific sources of polyketides. This review summarizes studies from 1973 to 2017 on the biosynthesis of natural products by -AT PKSs from species.