# Beta-Lactam Resistance Mechanisms of Staphylococcus aureus

> **NIH NIH R01** · UNIVERSITY OF NOTRE DAME · 2024 · $630,355

## Abstract

Project Summary/Abstract
Staphylococcus aureus is a problematic human bacterial pathogen, which is broadly resistant to b-lactam
antibiotics. This resistance is inducible and is conferred by a set of genes that encode a b-lactam antibiotic
sensor/signal transducer protein, a gene repressor and two resistance determinants (the BlaZ b-lactamase and
a unique penicillin-binding protein designated as PBP2a). A key feature of these processes is the recognition
of the antibiotic by the b-lactam sensor/signal transduce BlaR, an integral membrane protein. Recognition of
the antibiotic by the sensor domain of BlaR unleashes conformational changes through the membrane, which
lead to the activation of the protease domain on the cytoplasmic side. This process culminates in expression of
the genes for the antibiotic-resistance determinants. In Specific Aim 1, we describe the use of a fluorescent
tool in live S. aureus for discovery of agents that shut down the BlaR recognition of the b-lactam antibiotics,
which would reverse the resistance phenotype. A discovery funnel is outlined for analysis of structure-activity
relationship for these compounds. In Specific Aim 2 we communicate a discovery that the BlaZ b-lactamase is
incorporated to the surface of the cytoplasmic membrane in a lipidation- and phosphorylation-dependent
manner. We outline a method for purification of the membrane-anchored BlaZ for the purpose of the
identification of the sites of phosphorylation. The protein will be used in kinetic studies to compare to the non-
membrane-anchored BlaZ, which is not phosphorylated. Plans are detailed for X-ray crystallography for
characterization of the structural issues. The generality of the lipidation- and phosphorylation-dependent
anchoring of proteins to the membrane surface in S. aureus will be explored for 10 distinct proteins. In each
case, plans are outlined to identify the sites of phosphorylation to elucidate rules for phosphorylation and
membrane sequestration of these proteins. These studies will shed definitive light on the complex machinery
that S. aureus strains have evolved for resistance to b-lactam antibiotics.

## Key facts

- **NIH application ID:** 10745736
- **Project number:** 5R01AI104987-12
- **Recipient organization:** UNIVERSITY OF NOTRE DAME
- **Principal Investigator:** Shahriar Mobashery
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $630,355
- **Award type:** 5
- **Project period:** 2013-01-01 → 2027-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10745736

## Citation

> US National Institutes of Health, RePORTER application 10745736, Beta-Lactam Resistance Mechanisms of Staphylococcus aureus (5R01AI104987-12). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10745736. Licensed CC0.

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