Yi Tang, Chemical and Biomolecular Engineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, CA 90095
Iterative fungal polyketide synthases (PKSs) use a unique set of biochemical rules in the synthesis of complex polyketides. These rules dictate polyketide starter unit selection, chain length control, and post-PKS processing. In contrast to the bacterial PKSs, the biosynthetic mechanisms of fungal PKSs are not well understood and their potential for combinatorial biosynthesis has not yet been realized. This is largely due to difficulties associated with manipulating these megasynthases in their native or related fungal hosts, and with obtaining intact enzymes for biochemical analysis. In this work, we demonstrate the expression, reconstitution and engineering of several intact fungal megasynthases expressed from genetically simple microorganisms. We will discuss our recent work with 1) PKS4 from Gibberella fujikuroi that is involved in the synthesis of bikaverin; 2) PKS13 from Gibberella zeae which is a fungal macrolactone synthase in the synthesis of zearelenone; and 3) LovB from Aspergillus terreus which is the central PKS in the synthesis of lovastatin. These results set the stage for detailed characterization and protein engineering of fungal PKSs, and offer opportunities towards the enzymatic synthesis of new compounds.
