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Title: Biochemical and Structural Basis for Controlling Chemical Modularity in Fungal Polyketide Biosynthesis

Modular collaboration between iterative fungal polyketide synthases (IPKSs) is an important mechanism for generating structural diversity of polyketide natural products. Inter-PKS communication and substrate channeling are controlled in large by the starter unit acyl carrier protein transacylase (SAT) domain found in the accepting IPKS module. Here in this study, we reconstituted the modular biosynthesis of the benzaldehyde core of the chaetoviridin and chaetomugilin azaphilone natural products using the IPKSs CazF and CazM. Our studies revealed a critical role of CazM’s SAT domain in selectively transferring a highly reduced triketide product from CazF. In contrast, a more oxidized triketide that is also produced by CazF and required in later stages of biosynthesis of the final product is not recognized by the SAT domain. The structural basis for the acyl unit selectivity was uncovered by the first X-ray structure of a fungal SAT domain, highlighted by a covalent hexanoyl thioester intermediate in the SAT active site. Finally, the crystal structure of SAT domain will enable protein engineering efforts aimed at mixing and matching different IPKS modules for the biosynthesis of new compounds.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [2] ;  [3] ;  [5]
  1. Univ. of California, Los Angeles, CA (United States). Dept. of Chemical and Biomolecular Engineering
  2. Univ. of California, Los Angeles, CA (United States). DOE Inst. for Genomics and Proteomics
  3. Univ. of Alberta, Edmonton, AB (Canada). Dept. of Chemistry
  4. Univ. of Shizuoka (Japan). Dept. of Pharmaceutical Sciences
  5. Univ. of California, Los Angeles, CA (United States). Dept. of Chemical and Biomolecular Engineering; Univ. of California, Los Angeles, CA (United States). Dept. of Chemistry and Biochemistry
Publication Date:
OSTI Identifier:
1212209
Grant/Contract Number:
FC02-02ER63421; AC02-06CH11357; CHE-1048804; 5P41RR015301-10
Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 137; Journal Issue: 31; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org:
USDOE; National Institutes of Health (NIH); National Science Foundation (NSF)
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY