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PptAB Exports Rgg Quorum-Sensing Peptides in Streptococcus
Jennifer C Chang1, Michael J Federle1
1Department of Medicinal Chemistry and Pharmacognosy, Center for Biomolecular Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois, United States of America.
Plos One
|December 20, 2016
Summary
Streptococcus pyogenes PptAB transporter exports short hydrophobic peptides (SHPs). However, it only partially affects the secretion of Streptococcus mutans XIP pheromone, suggesting an alternative export pathway.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Genetics
Background:
- Peptide-pheromone signaling is crucial for bacterial communication and virulence.
- The Rgg2/Rgg3 signaling pathway in Streptococcus pyogenes regulates various cellular processes.
- ABC-type transporters, like PptAB, are involved in exporting molecules across cell membranes, but their specific roles in Gram-positive bacteria are often unclear.
Purpose of the Study:
- To identify genes involved in peptide-pheromone signaling in Streptococcus pyogenes.
- To investigate the function of the PptAB transporter in pheromone secretion.
- To determine if PptAB is the sole exporter for signaling peptides in related species like Streptococcus mutans.
Main Methods:
- Transposon mutagenesis screen in Streptococcus pyogenes to identify mutants with altered reporter activity.
- Mapping transposon insertion sites to identify mutated genes, including pptAB.
- Generating a pptAB deletion mutant in Streptococcus pyogenes and analyzing pheromone levels in culture supernatants.
- Generating a pptAB deletion mutant in Streptococcus mutans to assess its role in secreting both heterologous SHP peptides and endogenous XIP pheromone.
Main Results:
- Mutagenesis identified sixteen loci affecting peptide-pheromone signaling, with fourteen insertions mapping to pptAB.
- A Streptococcus pyogenes pptAB deletion mutant failed to secrete short hydrophobic peptides (SHPs).
- In Streptococcus mutans, PptAB was required for secretion of heterologous SHP peptides, but only partially affected secretion of the endogenous XIP pheromone, indicating a redundant or alternative secretion mechanism for XIP.
Conclusions:
- PptAB is a key exporter for short hydrophobic peptides (SHPs) in Streptococcus species.
- While PptAB contributes to XIP pheromone secretion in Streptococcus mutans, it is not the sole exporter, highlighting the existence of alternative secretion pathways for certain signaling peptides.
- The findings expand our understanding of pheromone transport mechanisms in Gram-positive bacteria.
