Journal
MOLECULAR MICROBIOLOGY
Volume 96, Issue 5, Pages 1069-1084Publisher
WILEY
DOI: 10.1111/mmi.12991
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Funding
- Centre National de la Recherche Scientifique
- University Paris-Sud, Electricite de France [RB2007-11]
- Agence Nationale de la Recherche [ANR-11-BSV3-01701]
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Deinococcus radiodurans is known for its extreme radioresistance. Comparative genomics identified a radiation-desiccation response (RDR) regulon comprising genes that are highly induced after DNA damage and containing a conserved motif (RDRM) upstream of their coding region. We demonstrated that the RDRM sequence is involved in cis-regulation of the RDR gene ddrBin vivo. Using a transposon mutagenesis approach, we showed that, in addition to ddrO encoding a predicted RDR repressor and irrE encoding a positive regulator recently shown to cleave DdrO in Deinococcusdeserti, two genes encoding -keto-glutarate dehydrogenase subunits are involved in ddrB regulation. In wild-type cells, the DdrO cell concentration decreased transiently in an IrrE-dependent manner at early times after irradiation. Using a conditional gene inactivation system, we showed that DdrO depletion enhanced expression of three RDR proteins, consistent with the hypothesis that DdrO acts as a repressor of the RDR regulon. DdrO-depleted cells loose viability and showed morphological changes evocative of an apoptotic-like response, including membrane blebbing, defects in cell division and DNA fragmentation. We propose that DNA repair and apoptotic-like death might be two responses mediated by the same regulators, IrrE and DdrO, but differently activated depending on the persistence of IrrE-dependent DdrO cleavage.
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