Mycobacterial nonhomologous end joining mediates mutagenic repair of chromosomal double-strand DNA breaks Journal Article


Authors: Stephanou, N. C.; Gao, F.; Bongiorno, P.; Ehrt, S.; Schnappinger, D.; Shuman, S.; Glickman, M. S.
Article Title: Mycobacterial nonhomologous end joining mediates mutagenic repair of chromosomal double-strand DNA breaks
Abstract: Bacterial nonhomologous end joining (NHEJ) is a recently described DNA repair pathway best characterized in mycobacteria. Bacterial NHEJ proteins LigD and Ku have been analyzed biochemically, and their roles in linear plasmid repair in vivo have been verified genetically; yet the contributions of NHEJ to repair of chromosomal DNA damage are unknown. Here we use an extensive set of NHEJ- and homologous recombination (HR)-deflcient Mycobacterium smegmatis strains to probe the importance of HR and NHEJ in repairing diverse types of chromosomal DNA damage. An M. smegmatis ΔrecA Δku double mutant has no apparent growth defect in vitro. Loss of the NHEJ components Ku and LigD had no effect on sensitivity to UV radiation, methyl methanesulfonate, or quinolone antibiotics. NHEJ deficiency had no effect on sensitivity to ionizing radiation in logarithmic- or early-stationary-phase cells but was required for ionizing radiation resistance in late stationary phase in 7H9 but not LB medium. In addition, NHEJ components were required for repair of I-SceI mediated chromosomal double-strand breaks (DSBs), and in the absence of HR, the NHEJ pathway rapidly mutates the chromosomal break site. The molecular outcomes of NHEJ-mediated chromosomal DSB repair involve predominantly single-nucleotide insertions at the break site, similar to previous findings using plasmid substrates. These findings demonstrate that prokaryotic NHEJ is specifically required for DSB repair in late stationary phase and can mediate mutagenic repair of homing endonuclease-generated chromosomal DSBs. Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Keywords: mutation; nonhuman; ultraviolet radiation; phenotype; dna damage; homologous recombination; dna repair; dose-response relationship, drug; bacterial strain; bacteria (microorganisms); dose-response relationship, radiation; dna strand breakage; bacterial proteins; ionizing radiation; dna breaks, double-stranded; radiosensitivity; chromosome breakage; base sequence; models, genetic; gene insertion; ultraviolet rays; bacterial dna; mycobacterium; corynebacterineae; quinoline derived antiinfective agent; chromosomes, bacterial; dna ligases; mycobacterium smegmatis; bacterial genetics; bacterial growth; microbial viability; bacterium mutant; mesylic acid methyl ester; gamma rays; prokaryota; rec a recombinases; methyl methanesulfonate; deoxyribonucleases, type ii site-specific; quinolones; bacterial chromosome
Journal Title: Journal of Bacteriology
Volume: 189
Issue: 14
ISSN: 0021-9193
Publisher: American Society for Microbiology  
Date Published: 2007-07-01
Start Page: 5237
End Page: 5246
Language: English
DOI: 10.1128/jb.00332-07
PUBMED: 17496093
PROVIDER: scopus
PMCID: PMC1951864
DOI/URL:
Notes: --- - "Cited By (since 1996): 28" - "Export Date: 17 November 2011" - "CODEN: JOBAA" - "Source: Scopus"
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MSK Authors
  1. Stewart H Shuman
    514 Shuman
  2. Feng Gao
    3 Gao