# Mechanistic details of key integral membrane enzymes for antimicrobial discovery

> **NIH NIH R01** · CALIFORNIA INSTITUTE OF TECHNOLOGY · 2023 · $442,563

## Abstract

Project Summary
Title: Mechanistic details of key integral-membrane enzymes for antimicrobial discovery
The increasing number of antibiotic resistant strains of bacteria represents a significant threat to human health,
making the development of novel therapeutic strategies critical. The major component of the bacterial cell wall
is the peptidoglycan layer that is a unique meshwork providing essential structural support; therefore,
identifying ways to weaken this layer is an ideal antibiotic strategy. Currently, numerous therapeutics target the
peptidoglycan synthesis pathway and their use has been extremely successful in medicine. The enzymes
involved in the pathway have been extensively characterized except in the case of the membrane components.
Most notable are MraY and MurG, essential proteins that catalyze the membrane steps of peptidoglycan
biosynthesis. There are a few known inhibitors of MraY, such as tunicamycin, demonstrating its potential as an
antibiotic target; however, none of them has found usefulness in the clinic. Our group has developed efficient
total synthesis schemes for two of the most promising natural products, capuramycin and muraymycin, and in
the last funding period we have leveraged this to create novel compounds with improved therapeutic potential.
In this proposal, we describe our plans to use our functional MraY homologs to solve structures in a lipid
environment with various inhibitors and substrate analogs by EM and X-ray crystallography. We have
developed a new assay for MurG that allowed us to identify novel inhibitors. We will further screen additional
compounds and solve their structures with MurG. We will further explore the MurG interaction with the lipid
bilayer and MraY. Our novel inhibitors, APPB and CPPB, have broad efficacy against bacterial pathogens and
show potential as anti-cancer therapeutics. We will leverage the structural work to design the next round of
compound libraries. The breadth of effectiveness leads us to pursue structures of other phosphotransferases,
bacterial WecA and human DPAGT1, in complex with our compounds. This will allow for more targeted small
molecule development. The aims are to 1) perform structural and mechanistic studies of MraY and the
development of inhibitors, 2) carry out mechanistic and structural studies of MurG, and 3) develop novel and
improved phosphotransferase inhibitors. Our combined team of structural biologists and synthetic chemists
provides an innovative approach to achieve these important goals.

## Key facts

- **NIH application ID:** 10653003
- **Project number:** 5R01GM114611-07
- **Recipient organization:** CALIFORNIA INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** William M. Clemons
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $442,563
- **Award type:** 5
- **Project period:** 2016-08-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10653003

## Citation

> US National Institutes of Health, RePORTER application 10653003, Mechanistic details of key integral membrane enzymes for antimicrobial discovery (5R01GM114611-07). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10653003. Licensed CC0.

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