Federal Grant Award Summary

The University of California, San Diego received a $439,500 Project Grant from the National Center for Complementary and Integrative Health under the Research and Training in Complementary and Integrative Health program (CFDA 93.213) for the period April 1, 2026 through March 31, 2028. The award supports the development of advanced technologies and methodologies to enable high-resolution structural analysis of native polyketide synthase (PKS) megasynthases using cryo-electron microscopy (cryo-EM). The research addresses significant technical barriers in structural biology by developing two critical tools: first, methods to convert native holo-PKS to their cognate apo-forms to enable crosslinking within native PKS systems, and second, protein isolation methodologies for very large megasynthases (500 kilodaltons to 2 megadaltons) extracted directly from native producer organisms' proteomes.

The project utilizes the amphotericin synthase pathway from Streptomyces nodosus as a model system to validate these technologies and demonstrate their applicability to polyketide natural products research. By developing dual site-selective crosslinking tools that enforce dynamic constraints on these highly flexible megaproteins, the research aims to achieve previously unattainable high-resolution cryo-EM structures of complete, native synthase complexes. These deliverables represent a fundamental advancement in molecular-level understanding of PKS structure and function, with direct applications to polyketide-based drug discovery and manufacturing.