All domains of life produce peptidic natural products that play roles as diverse as quorum sensing molecules and redox cofactors. The ability of these peptides to function as antibacterial, antiviral, or anticancer agents makes understanding their biosynthesis an important area of contemporary research. Peptide-based secondary metabolites are produced by distinct biosynthetic pathways that differ in whether the peptide is synthesized by the action of non-ribosomal peptide synthetases (NRPS), or ribosomally produced from a genomically encoded orf. These peptides are often extensively modified. While in the NRPS systems many of the modifications occur concurrently with peptide synthesis, the ribosomally encoded peptides undergo posttranslational modification. These so-called ribosomally encoded posttranslationally modified polypeptides (RiPP) are a new emerging class of polypeptides that have extensive modifications that are introduced by mechansims that are mostly poorly understood. This application will focus on enzymes introduce sulfur-to-alpha carbon thioether crosslinks into ribosomally encoded peptides to produce sactipeptides. These linkages are distinct from the well-studied lanthipeptide, where thioether crosslinks form between a Cys residue and a dehydrated Thr/Ser. The sactipeptide maturases are members of the radical SAM family of enzymes and catalyze thioether crosslinks by a radical- mediated reaction that is not understood. While The biochemical, spectroscopic, and structural studies in this application will lead to a mechanistic paradigm for this important class of enzymes. While sactipeptides themselves have various therapeutic uses, understanding the substrate profiles and mechanisms of these enzymes would provide a tool for synthesis of crosslinked peptides, which are increasing finding utility in the clinic.

Public Health Relevance

Peptide-based agents are increasingly finding utility in the clinic. Introduction of crosslinks and modifications that stabilize them towards degradation in the cell is key for their expanded adoption. This application focuses on understanding the mechanism of sulfur-to-carbon crosslink formation in a class of peptides, with the goal of obtaining insights in to engineering the system in the future to expand the repertoire of tools for synthesis of novel peptide-based therapeutic agents.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM120638-01
Application #
9169902
Study Section
Macromolecular Structure and Function A Study Section (MSFA)
Program Officer
Anderson, Vernon
Project Start
2016-08-01
Project End
2020-07-31
Budget Start
2016-08-01
Budget End
2017-07-31
Support Year
1
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of Utah
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
009095365
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
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