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A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
Published on: February 19, 2019
The cryptic competence pathway in Streptococcus pyogenes is controlled by a peptide pheromone.
Lauren Mashburn-Warren1, Donald A Morrison, Michael J Federle
1Center for Pharmaceutical Biotechnology, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois, USA.
Journal of Bacteriology
|June 26, 2012
Summary
Streptococcus pyogenes can activate competence genes via a peptide pheromone but cannot take up DNA, blocking natural genetic transformation. This study identifies a key step in bacterial evolution and DNA uptake regulation.
Area of Science:
- Microbiology
- Bacterial Genetics
- Molecular Biology
Background:
- Horizontal gene transfer is crucial for bacterial evolution, with natural genetic transformation being a key mechanism.
- Bacterial competence, a state enabling DNA uptake, is regulated by complex signaling pathways and master regulators like SigX.
- The type II ComRS quorum-sensing system, involving Rgg regulators and peptide pheromones, controls competence in some streptococci.
Purpose of the Study:
- To investigate the regulation of the master competence regulator SigX in Streptococcus pyogenes.
- To understand the role of the type II ComRS quorum-sensing system in S. pyogenes competence development.
- To identify the specific barriers to natural genetic transformation in S. pyogenes.
Main Methods:
- Analysis of sigX activation by peptide pheromones and Rgg regulators.
- Confirmation of SigX functionality and its influence on competence gene expression.
- Assessment of SigX stability mediated by the ClpP protease.
- Genomic analysis of competence-related genes in S. pyogenes.
- Experimental testing of transformation efficiency using radiolabeled DNA.
Main Results:
- SigX in S. pyogenes is naturally induced by a small-peptide pheromone and an Rgg regulator from the type II ComRS class.
- SigX is functional and activates downstream competence genes, with its stability regulated by ClpP.
- Despite possessing intact competence genes and SigX induction, S. pyogenes is blocked at the DNA uptake stage, preventing transformation.
Conclusions:
- The type II ComRS system regulates SigX induction in S. pyogenes, demonstrating a conserved mechanism for competence activation.
- S. pyogenes exhibits a specific block in DNA uptake, rendering it non-transformable under laboratory conditions despite competence gene presence.
- This finding highlights a critical regulatory checkpoint in bacterial natural genetic transformation and provides insights into streptococcal evolution.
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