MazF-induced Growth Inhibition and Persister Generation in Escherichia coli

Tripathi, Arti and Dewan, Pooja C and Siddique, Shahbaz A and Varadarajan, Raghavan (2014) MazF-induced Growth Inhibition and Persister Generation in Escherichia coli. In: JOURNAL OF BIOLOGICAL CHEMISTRY, 289 (7). pp. 4191-4205.

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Abstract

Background: MazEF is a chromosomally encoded bacterial toxin-antitoxin system whose cellular role is controversial. Results: Expression of chromosomal MazF inhibits cell killing by multiple antibiotics in a Lon and ClpP dependent manner. Conclusion: MazF is involved in reversible growth inhibition and bacterial drug tolerance. Significance: Inactive, active-site toxin mutants yield functional insights by selectively activating the corresponding WT toxin in vivo. Toxin-antitoxin systems are ubiquitous in nature and present on the chromosomes of both bacteria and archaea. MazEF is a type II toxin-antitoxin system present on the chromosome of Escherichia coli and other bacteria. Whether MazEF is involved in programmed cell death or reversible growth inhibition and bacterial persistence is a matter of debate. In the present work the role of MazF in bacterial physiology was studied by using an inactive, active-site mutant of MazF, E24A, to activate WT MazF expression from its own promoter. The ectopic expression of E24A MazF in a strain containing WT mazEF resulted in reversible growth arrest. Normal growth resumed on inhibiting the expression of E24A MazF. MazF-mediated growth arrest resulted in an increase in survival of bacterial cells during antibiotic stress. This was studied by activation of mazEF either by overexpression of an inactive, active-site mutant or pre-exposure to a sublethal dose of antibiotic. The MazF-mediated persistence phenotype was found to be independent of RecA and dependent on the presence of the ClpP and Lon proteases. This study confirms the role of MazEF in reversible growth inhibition and persistence.

Item Type:	Journal Article
Publication:	JOURNAL OF BIOLOGICAL CHEMISTRY
Publisher:	AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Additional Information:	copyright for this article belongs to AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3996 USA
Keywords:	Antibiotics; Cell Death; Mutant; Protein Degradation; Protein Synthesis; Toxin-Antitoxin; Inactive; Active-site Mutant; Bacteriostasis; Antibiotic Tolerance
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	12 Jun 2014 10:41
Last Modified:	12 Jun 2014 10:41
URI:	http://eprints.iisc.ac.in/id/eprint/49197

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