Abstract

: This project is a continuation of a broadly based investigation into the regulatory mechanisms that control the production of virulence factors and other exoproteins in Staphylococcus aureus, with an extension to the regulation of superantigen toxin synthesis in Streptococcus pyogenes. The present focus is on the mechanism of action of the agr effector molecule, the 514 nt RNAIII, and is based on the hypothesis that RNAIII interacts with internal regulatory mediators. We have found that a key intracellular mediator is the 2-component sae system, which is transcriptionally activated by RNAIII and which is required for the expression of many of the exoprotein genes. There are four specific aims: 1. To characterize the central pathway from agr via RNAIII to target genes. 2. To determine the mechanisms by which external stimuli and certain growth conditions affect the expression of genes in the agr regulon. 3. To analyze by means of reporter gene fusions the expression of different regulatory and target genes. 4. To determine whether the regulation of speA and other toxin genes by group A hemolytic streptococci is similar to staphylococcal regulation of virulence factors.
In Aim 1, oligonucleotide arrays will be used to define the agr regulon and overlapping regulons governed by other global regulators of virulence.
In Aim 2, the mechanism by which RNAIII activates the intracellular mediator sae will be identified, and its role in regulating target gene transcription defined.
In Aim 3, the focus will be on the mechanism by which certain external stimuli interact with the agr pathway, starting with a determination of the sets of genes (stimulons) that are affected by particular environmental conditions. It is proposed to compare the effects of these stimuli and of various regulatory mutations in planktonic cultures with their effects in bioflims.
In Aim 4, a continuation of a study in which we have identified an autoinducer of streptococcal erythogenic toxin (SPEA) synthesis, is proposed.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI030138-11A1
Application #
6327152
Study Section
Special Emphasis Panel (ZRG1-BM-1 (03))
Project Start
1991-09-01
Project End
2006-02-28
Budget Start
2001-03-01
Budget End
2002-02-28
Support Year
11
Fiscal Year
2001
Total Cost
$154,688
Indirect Cost

  Institution

Name
New York University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
City
New York
State
NY
Country
United States
Zip Code
10016

  Publications

Geisinger, Edward; Chen, John; Novick, Richard P (2012) Allele-dependent differences in quorum-sensing dynamics result in variant expression of virulence genes in Staphylococcus aureus. J Bacteriol 194:2854-64
Smyth, Davida S; Kafer, Jared M; Wasserman, Gregory A et al. (2012) Nasal carriage as a source of agr-defective Staphylococcus aureus bacteremia. J Infect Dis 206:1168-77
Shopsin, Bo; Eaton, Christian; Wasserman, Gregory A et al. (2010) Mutations in agr do not persist in natural populations of methicillin-resistant Staphylococcus aureus. J Infect Dis 202:1593-9
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
Chen, John; Novick, Richard P (2007) svrA, a multi-drug exporter, does not control agr. Microbiology 153:1604-8
Adhikari, Rajan P; Arvidson, Staffan; Novick, Richard P (2007) A nonsense mutation in agrA accounts for the defect in agr expression and the avirulence of Staphylococcus aureus 8325-4 traP::kan. Infect Immun 75:4534-40
Geisinger, Edward; Adhikari, Rajan P; Jin, Ruzhong et al. (2006) Inhibition of rot translation by RNAIII, a key feature of agr function. Mol Microbiol 61:1038-48
Ji, Guangyong; Pei, Wuhong; Zhang, Linsheng et al. (2005) Staphylococcus intermedius produces a functional agr autoinducing peptide containing a cyclic lactone. J Bacteriol 187:3139-50
Weinrick, Brian; Dunman, Paul M; McAleese, Fionnuala et al. (2004) Effect of mild acid on gene expression in Staphylococcus aureus. J Bacteriol 186:8407-23
Charpentier, Emmanuelle; Anton, Ana I; Barry, Peter et al. (2004) Novel cassette-based shuttle vector system for gram-positive bacteria. Appl Environ Microbiol 70:6076-85

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