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Purification of a High Molecular Mass Protein in Streptococcus mutans
Published on: September 14, 2019
Three gene products govern (p)ppGpp production by Streptococcus mutans
José A Lemos1, Vanessa K Lin, Marcelle M Nascimento
1Department of Oral Biology, University of Florida College of Dentistry, PO Box 100424, Gainesville, FL 32610, USA.
Molecular Microbiology
|August 24, 2007
Summary
Streptococcus mutans utilizes novel enzymes RelP and RelQ for (p)ppGpp synthesis, challenging the established RelA-centric model in Gram-positive bacteria. This discovery reveals complex alarmone regulation and potential new targets in pathogenic streptococci.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Physiology
Background:
- The canonical model identifies RelA as the primary enzyme for guanosine tetra- and penta-phosphate ((p)ppGpp) synthesis and degradation in Gram-positive bacteria.
- This model is challenged by the unique regulatory mechanisms observed in Streptococcus mutans, a significant human oral pathogen.
Purpose of the Study:
- To identify and characterize novel enzymes involved in (p)ppGpp metabolism in Streptococcus mutans.
- To elucidate the regulatory network governing (p)ppGpp production in S. mutans and compare it to established bacterial paradigms.
- To investigate the distribution and potential role of these novel enzymes in other pathogenic streptococci.
Main Methods:
- Gene identification and characterization of putative (p)ppGpp synthetases (relP and relQ).
- Construction and analysis of various S. mutans mutant strains lacking combinations of synthetase genes.
- Functional complementation studies in a (p)ppGpp(0) Escherichia coli strain and S. mutans mutants.
- Analysis of gene co-transcription with two-component signal transduction systems (TCS).
Main Results:
- Identification and characterization of two novel (p)ppGpp synthetases, RelP and RelQ, in S. mutans.
- RelP is co-transcribed with a two-component signal transduction system (TCS).
- Mutational analyses revealed a complex regulon for (p)ppGpp synthesis in S. mutans, distinct from other bacteria.
- Expression of relP and relQ restored growth and (p)ppGpp production in deficient E. coli and S. mutans strains.
Conclusions:
- The dogma of RelA as the sole (p)ppGpp regulator is not applicable to Streptococcus mutans, which employs RelP and RelQ for synthesis.
- S. mutans exhibits unique strategies for alarmone production, suggesting a complex regulatory network.
- The presence of RelQ, RelP, and associated TCS in other pathogenic streptococci offers new insights into pathogen survival strategies.
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