Functional and Structural Studies on the Esperamicin Thioesterase and Progress toward Understanding Enediyne Core Biosynthesis
Year: 2025
Type: article
Abstract: Enediynes are among the most potent antitumor and antibacterial natural products. Studies on their biosynthetic pathways have identified a shared, linear polyene precursor generated from an iterative type I polyketide synthase (PKSE) as the source of the enediyne warhead. A key step is the release of this polyene from the PKSE by a discrete thioesterase (TE). Here, we used X-ray crystallography, site-directed mutagenesis, and heterologous coexpression of PKSEs and TEs to elucidate how enediyne TEs mediate the production of the polyene. We solved the structure of wild-type EspE7 from esperamicin producer Actinomodura verrucosospora . The substrate binding pocket was also defined upon serendipitous cocrystallization of an EspE7 mutant with a fatty acyl-CoA ligand. Structural data and in vitro activity assays with EspE7 mutants provide strong evidence that Glu68 in EspE7 and the analogous Glu residue in other enediyne TEs functions as a key catalytic residue, thus supporting a hydrolysis mechanism for enediyne TEs that aligns with that of Pseudomonas sp. 4-HB-CoA TE. Furthermore, combinations of 9- and 10-membered enediyne PKSEs and TEs produced 1,3,5,7,9,11,13-pentadecaheptaene ( 1 ) as the major product. Thus, the data further support previous conclusions that 1 serves as the sole precursor for the biosynthesis of all enediyne cores.
Source: Journal of Natural Products
Authors: Erome D. Hankore, Mitchell D. Miller, Abigael J. Kosgei, Weijun Xu, Kemin Tan, Michael Endres, Minakshi Bhardwaj, Grazyna Joachimiak, Andrzej Joachimiak, George N. Phillips, Jon S. Thorson, Steven G. Van Lanen
Language: English
Subfield: Pharmacology
Field: Medicine
Domain: Health Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, Welch Foundation, National Institutes of Health, Office of Science, BioXFEL Science and Technology Center, National Cancer Institute, National Institute of General Medical Sciences, Biological and Environmental Research, Argonne National Laboratory
Awards: G102163711, G107546177, G1313983767, G1325940910, G1664757510, G2287611682, G240744221, G262962599, G2857925935, G3039663548, G3075337988, G3127483976, G3152346458, G3424175725, High-Speed High-Sensitivity Detector for X-ray Micro-Crystallography at GM/CA@APS, G3913106684, G409777406, G4356617607, G4787385760, G498139845, G513797252, G5607048534, G6072549038, Platform technologies for understanding and exploiting methylation, G6848031779, G6918803902, G7304453980, G8473838722, G9000014584, GM/CA@APS: A Macromolecular Crystallography Resource, COBRE for Translational Chemical Biology, Biology with X-ray Lasers, G969889393, G992861146, G993149817
OpenAlex ID: W4415009627