A research program will be undertaken to study agr signal transduction in the commensal pathogen, Staphylococcus aureus. The accessory gene regulator (agr) locus found in all staphylococci encodes a quorum sensing (QS) circuit that controls the expression of virulence and other accessory genes. It consists of two oppositely oriented transcriptional units, of which one encodes four proteins, AgrBDCA, involved in production and sensing of an autoinducer peptide (AIP), and the other encodes a regulatory RNA that is the effector of target gene regulation. The finding that staphylococcal virulence can be inhibited through antagonism of this QS pathway has fueled tremendous interest in understanding the detailed mechanisms at play throughout the circuit. Building on recent breakthroughs that have allowed us to reconstitute much as the quorum sensing circuit using purified components, we propose to integrate chemical, biochemical, biophysical and genetic tools for the purpose of obtaining a deeper understanding into the molecular processes underlying the production and sensing of the autoinducer peptide (AIP) pheromone that is central to agr regulation. The program will move forward in three directions:
Aim 1, identifying the key missing players in AIP biosynthesis;
Aim 2, understanding how agonism and antagonism of the QS system relates to newly discovered conformational changes in the AIP receptor, AgrC, and;
Aim 3, identifying novel modulators of agr through sophisticated target-based screens. These studies will lay the groundwork for the development of therapeutic strategies targeting agr, but also contribute to a fundamental understanding of QS systems of this type, which are pervasive in the low-GC bacterial phylum, Firmicutes.

Public Health Relevance

Staphylococcus aureus (S. aureus) is an opportunistic pathogen capable of invading mucous membranes or soft tissue; once invasion occurs, the bacterium deploys a diverse arsenal of virulence factors to evade the host immune system and to facilitate spread of the infection in the host environment. A research program will be undertaken to study the central quorum sensing (QS) circuit, termed agr, which regulates the onset of virulence as a function of bacterial population size. Building on recent breakthroughs that have allowed us to reconstitute much of the circuit using purified components, we propose to integrate chemical, biochemical, biophysical and genetic tools to gain a deeper understanding into the molecular processes underlying agr regulation; these studies will provide fundamental insights into how a QS circuit such as agr operates at the molecular level and will lay the foundation for the development of new strategies for treating Staphylococcus aureus infections.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI042783-17
Application #
9427947
Study Section
Synthetic and Biological Chemistry B Study Section (SBCB)
Program Officer
Huntley, Clayton C
Project Start
1998-05-15
Project End
2022-01-31
Budget Start
2018-02-01
Budget End
2019-01-31
Support Year
17
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Princeton University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
002484665
City
Princeton
State
NJ
Country
United States
Zip Code
08543
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Wang, Boyuan; Zhao, Aishan; Xie, Qian et al. (2017) Functional Plasticity of the AgrC Receptor Histidine Kinase Required for Staphylococcal Virulence. Cell Chem Biol 24:76-86
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Johnson, Jeffrey G; Wang, Boyuan; Debelouchina, Galia T et al. (2015) Increasing AIP Macrocycle Size Reveals Key Features of agr Activation in Staphylococcus aureus. Chembiochem 16:1093-100
Wang, Boyuan; Zhao, Aishan; Novick, Richard P et al. (2014) Activation and inhibition of the receptor histidine kinase AgrC occurs through opposite helical transduction motions. Mol Cell 53:929-40
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George Cisar, Elizabeth A; Geisinger, Edward; Muir, Tom W et al. (2009) Symmetric signalling within asymmetric dimers of the Staphylococcus aureus receptor histidine kinase AgrC. Mol Microbiol 74:44-57
Geisinger, Edward; Muir, Tom W; Novick, Richard P (2009) agr receptor mutants reveal distinct modes of inhibition by staphylococcal autoinducing peptides. Proc Natl Acad Sci U S A 106:1216-21

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