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Constitutive SOS expression and damage‐inducible AddAB‐mediated recombinational repair systems for Coxiella burnetii as potential adaptations for survival within macrophages
Author(s) -
Mertens Katja,
Lantsheer Letty,
Ennis Don G.,
Samuel James E.
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06373.x
Subject(s) - repressor lexa , biology , coxiella burnetii , sos response , recbcd , escherichia coli , dna repair , photorhabdus luminescens , gene , genetics , mutant , microbiology and biotechnology , repressor , gene expression
Summary Coxiella burnetii , a Gram‐negative obligate intracellular pathogen, replicates within an parasitophorous vacuole with lysosomal characteristics. To understand how C. burnetii maintains genomic integrity in this environment, a database search for genes involved in DNA repair was performed. Major components of repair, SOS response and recombination were identified, including recA and ruvABC , but lexA and recBCD were absent. Instead, C. burnetii possesses addAB orthologous genes, functional equivalents to recBCD . Survival after treatment with UV, mitomycin C (MC) or methyl methanesulfonate (MMS), as well as homologous recombination in Hfr mating was restored in Escherichia coli deletion strains by C. burnetii recA or addAB . Despite the absence of LexA, co‐protease activity for C. burnetii RecA was demonstrated. Dominant‐negative inhibition of C. burnetii RecA by recA mutant alleles, modelled after E. coli recA1 and recA56 , was observed and more apparent with expression of C. burnetii RecAG159D mutant protein. Expression of a subset of repair genes in C. burnetii was monitored and, in contrast to the non‐inducible E. coli recBCD , addAB expression was strongly upregulated under oxidative stress. Constitutive SOS gene expression due to the lack of LexA and induction of AddAB likely reflect a unique repair adaptation of C. burnetii to its hostile niche.