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The tolC locus affects the expression of sbmA through σE activity increase
Natalia S Corbalán1, Conrado Adler, Ricardo E de Cristóbal
1Departamento de Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas (INSIBIO), Instituto de Química Biológica Dr. Bernabé Bloj, Tucumán, Argentina.
FEMS Microbiology Letters
|August 26, 2010
Summary
A tolC mutation in E. coli increases the expression of the SbmA protein, which transports peptides. This upregulation is dependent on the sigma E (σE) stress response pathway, suggesting a compensatory mechanism for cell envelope stress.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Physiology
Background:
- The SbmA protein facilitates the transport of various peptides into Escherichia coli.
- The precise physiological function of SbmA remains unclear, despite its presence in diverse bacteria.
- Previous studies indicated that combined sbmA and tolC mutations enhance tetracycline susceptibility in E. coli.
Purpose of the Study:
- To investigate the regulation of sbmA gene expression in a tolC mutant background.
- To elucidate the molecular mechanisms underlying the observed changes in sbmA expression.
- To determine the role of the sigma E (σE) pathway in sbmA regulation.
Main Methods:
- Analyzing sbmA expression in tolC mutant E. coli strains.
- Investigating the involvement of RpoS and micF in sbmA regulation.
- Assessing the impact of tolC mutations on known σE-dependent promoters.
- Evaluating sbmA expression in rpoE-null strains.
Main Results:
- sbmA expression was significantly increased in a tolC mutant background.
- The upregulation of sbmA in tolC mutants was dependent on the sigma E (σE) activity.
- Elimination of σE abolished sbmA expression, confirming its positive regulatory role.
- The tolC mutation induced expression of other σE-dependent promoters.
Conclusions:
- The tolC mutation positively regulates sbmA expression in a σE-dependent manner.
- This regulatory mechanism may represent a compensatory response to cell envelope stress.
- The findings provide insights into the intricate regulatory networks governing bacterial peptide transport and stress responses.
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