Related Experiment Video
Updated: May 9, 2026
09:25
Implementation of a Permeable Membrane Insert-based Infection System to Study the Effects of Secreted Bacterial Toxins on Mammalian Host Cells
Published on: August 19, 2016
Redundant group a streptococcus signaling peptides exhibit unique activation potentials
Breah LaSarre1, Jennifer C Chang, Michael J Federle
1Department of Medicinal Chemistry and Pharmacognosy, Center for Pharmaceutical Biotechnology, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA.
Journal of Bacteriology
|July 23, 2013
Summary
Streptococcus pyogenes quorum sensing (QS) uses multiple peptides, SHP2 and SHP3, to activate systems. Peptide production differences, not signaling, explain their distinct roles in QS activation.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Communication
Background:
- Bacterial quorum sensing (QS) regulates gene expression using signaling molecules.
- Gram-positive bacteria often use peptide signaling molecules for QS.
- Streptococcus pyogenes possesses a unique QS system involving multiple signaling peptides, Rgg2/3.
Purpose of the Study:
- To investigate the roles of SHP2 and SHP3 peptides in activating the Rgg2/3 QS system in Streptococcus pyogenes.
- To determine the impact of shp gene dosage and peptide identity on QS circuit activation.
- To elucidate the factors contributing to the differential activity of SHP2 and SHP3.
Main Methods:
- Utilized transcriptional reporters to monitor QS system activity.
- Generated isogenic Streptococcus pyogenes mutants to study shp gene function.
- Employed synthetic peptides and gene mutants to analyze peptide production and signaling.
Main Results:
- shp gene dosage significantly influences Rgg2/3 system induction; lower dosage leads to reduced or absent induction.
- shp3 demonstrates a greater capacity to support Rgg2/3 system activation compared to shp2.
- Disparities in endogenous peptide activity stem from production differences, influenced by N-terminal regions, rather than signaling capabilities.
Conclusions:
- shp gene dosage is a critical factor in regulating QS system activation in Streptococcus pyogenes.
- SHP3 is a more potent activator of the Rgg2/3 system than SHP2.
- The N-terminal regions of SHP peptides modulate their production efficiency, affecting overall QS system activation potential.
Related Concept Videos
01:28Regulation of Bacterial Virulence
Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
01:30Bacterial Signaling
Bacterial signaling can occur within bacteria (intracellular) or between bacteria (intercellular). At times, a group of bacteria behaves like a community. To achieve this, they engage in quorum sensing, the perception of higher cell density that causes changes in gene expression. Quorum sensing involves both extracellular and intracellular signaling. The signaling cascade starts with a molecule called an autoinducer (AI). Individual bacteria produce AIs that move out of the bacterial cell...
01:22Amplifying Signals via Enzymatic Cascade
When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze the...
01:28Gene Regulation in Microbial Communities: Quorum Sensing
Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
01:20The JAK-STAT Signaling Pathway
Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as SH2...
01:22Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...