Induction of the homologous recombination system by hexavalent chromium in Rhizobium etli

Santoyo, Gustavo; Valdez-Martínez, Gabriela

doi:10.1016/j.micres.2014.06.003

Cited by 5 publications

(1 citation statement)

References 30 publications

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“…Experimental evidence presented here confirmed this suggestion, since the absence of RecA and UvrA, an essential factor of the NER system, strongly sensitized B. subtilis to chromate treatment. In line with our results, it was reported that the absence of a functional HR system increased the sensitivity of Rhizobium etli to the noxious effects of chromate (55). Based on these observations, we postulate that RecA-dependent HR is required for processing of single-and doublestrand breaks elicited directly or indirectly by Cr(VI) treatment (52,53).…”

Section: Discussionsupporting

confidence: 92%

Roles of Bacillus subtilis RecA, Nucleotide Excision Repair, and Translesion Synthesis Polymerases in Counteracting Cr(VI)-Promoted DNA Damage

et al. 2019

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Bacteria deploy global programs of gene expression, including components of the SOS response, to counteract the cytotoxic and genotoxic effects of environmental DNA-damaging factors. Here we report that genetic damage promoted by hexavalent chromium elicited the SOS response in Bacillus subtilis, as evidenced by the induction of transcriptional uvrA-lacZ, recA-lacZ, and P recA -gfp fusions. Accordingly, B. subtilis strains deficient in homologous recombination (RecA) and nucleotide excision repair (NER) (UvrA), components of the SOS response, were significantly more sensitive to Cr(VI) treatment than were cells of the wild-type strain. These results strongly suggest that Cr(VI) induces the formation in growing B. subtilis cells of cytotoxic and genotoxic bulky DNA lesions that are processed by RecA and/or the NER pathways. In agreement with this notion, Cr(VI) significantly increased the formation of DNA-protein cross-links (DPCs) and induced mutagenesis in recA-and uvrA-deficient B. subtilis strains, through a pathway that required YqjH/YqjWmediated translesion synthesis. We conclude that Cr(VI) promotes mutagenesis and cell death in B. subtilis by a mechanism that involves the formation of DPCs and that such deleterious effects are counteracted by both the NER and homologous recombination pathways, belonging to the RecA-dependent SOS system. IMPORTANCE It has been shown that, following permeation of cell barriers, Cr(VI) kills B. subtilis cells following a mechanism of reactive oxygen species-promoted DNA damage, which is counteracted by the guanine oxidized repair system. Here we report a distinct mechanism of Cr(VI)-promoted DNA damage that involves production of DPCs capable of eliciting the bacterial SOS response. We also report that the NER and homologous recombination (RecA) repair pathways, as well as low-fidelity DNA polymerases, counteract this metal-induced mechanism of killing in B. subtilis. Hence, our results contribute to an understanding of how environmental pollutants activate global programs of gene expression that allow bacteria to contend with the cytotoxic and genotoxic effects of heavy metals.

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Section: Discussionsupporting

confidence: 92%