Peptidyl nucleosides (PNs) are naturally occurring antifungal agents active against multiple pathogenic fungi such as the causal agent of Valley Fever. They also exhibit potent synergistic effects with clinically approved antifungal drugs. Our long-term goal is to provide a comprehensive understanding of both the biosynthesis of PNs and their mode of action. The current application focuses on the biosynthesis of PNs. Understanding the PN biosynthetic pathways will provide a basis for creating structurally diverse PN analogs through engineered biosynthesis, semi synthesis and genome mining. In this application, we will establish the common steps in PN biosynthesis by testing the central hypothesis that the structural features common to all PNs (aminohexuronic acid and its amide linkage to an amino acid) are biosynthesized through the action of seven conserved enzymes.
In Aim 1, NikJ, a newly identified free radical dependent enzyme responsible for the synthesis of a key cyclic nucleotide intermediate, will be mechanistically characterized.
In Aim 2, NikS, the enzyme responsible for the ligation of the N-terminal amino acid to nucleoside (aminohexuronic acid), will be characterized for both its substrate specificity and its potential for use in the chemoenzymatic preparation of PNs.
In Aim 3, the enzymes responsible for aminohexuronic acid formation will be identified through gene knockout experiments. The proposed research is significant because it will provide a basis for the future biosynthetic and chemoenzymatic generation of novel therapeutic PNs.

Public Health Relevance

The proposed research is relevant to public health because peptidyl nucleosides exhibit potent in vivo antifungal activities against fungi pathogenic to humans. Understanding their biosynthesis is an important step for their successful development into clinically useful molecules. Therefore, the proposed research will contribute to developing fundamental knowledge that will help to combat fungal infectious diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM115729-03
Application #
9302492
Study Section
Macromolecular Structure and Function A Study Section (MSFA)
Program Officer
Fabian, Miles
Project Start
2015-07-01
Project End
2020-06-30
Budget Start
2017-07-01
Budget End
2018-06-30
Support Year
3
Fiscal Year
2017
Total Cost
Indirect Cost
Name
Duke University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
044387793
City
Durham
State
NC
Country
United States
Zip Code
27705
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