MazF-induced Growth Inhibition and Persister Generation in Escherichia coli

• Published in: The Journal of biological chemistry Vol. 289; no. 7; pp. 4191 - 4205
• Main Authors: Tripathi, Arti, Dewan, Pooja C., Siddique, Shahbaz A., Varadarajan, Raghavan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 14.02.2014; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Substitution; Anti-Bacterial Agents - pharmacology; Antibiotic Tolerance; Antibiotics; Bacteriostasis; Catalytic Domain; Cell Death; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Endopeptidase Clp - genetics; Endopeptidase Clp - metabolism; Endoribonucleases - genetics; Endoribonucleases - metabolism; Escherichia coli K12 - genetics; Escherichia coli K12 - growth & development; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Inactive, Active-site Mutant; Microbiology; Mutant; Mutation, Missense; Protease La - genetics; Protease La - metabolism; Protein Degradation; Protein Synthesis; Rec A Recombinases - genetics; Rec A Recombinases - metabolism; Stress, Physiological - drug effects; Stress, Physiological - physiology; Toxin-Antitoxin; Antibiotic Tolerance; Inactive, Active-site Mutant; Protein Synthesis; Toxin-Antitoxin; Antibiotics; Cell Death; Mutant; Bacteriostasis; Protein Degradation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M113.510511

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. MazEF is a chromosomally encoded bacterial toxin-antitoxin system whose cellular role is controversial. Expression of chromosomal MazF inhibits cell killing by multiple antibiotics in a Lon and ClpP dependent manner. MazF is involved in reversible growth inhibition and bacterial drug tolerance. Inactive, active-site toxin mutants yield functional insights by selectively activating the corresponding WT toxin in vivo.