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Radiation response in D einococcus deserti : IrrE is a metalloprotease that cleaves repressor protein DdrO
Author(s) -
Ludanyi Monika,
Blanchard Laurence,
Dulermo Rémi,
Brandelet Géraldine,
Bellanger Laurent,
Pignol David,
Lemaire David,
Groot Arjan
Publication year - 2014
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/mmi.12774
Subject(s) - biology , repressor , gene , metalloproteinase , microbiology and biotechnology , cleavage (geology) , genetics , gene expression , matrix metalloproteinase , fracture (geology) , paleontology
Summary D einococcus bacteria are famous for their extreme radiation tolerance. The IrrE protein was shown to be essential for radiation tolerance and, in an unelucidated manner, for induction of a number of genes in response to radiation, including recA and other DNA repair genes. Earlier studies indicated that IrrE could be a zinc peptidase, but proteolytic activity was not demonstrated. Here, using several in vivo and in vitro experiments, IrrE from D einococcus deserti was found to interact with DdrO , a predicted regulator encoded by a radiation‐induced gene that is, like irrE , highly conserved in D einococcus . Moreover, IrrE was found to cleave DdrO in vitro and when the proteins were coexpressed in E scherichia coli . This cleavage was not observed in the presence of metal chelator EDTA or when IrrE contains a mutation in the conserved active‐site motif of metallopeptidases. In D . deserti , IrrE ‐dependent cleavage of DdrO was observed after exposure to radiation. Furthermore, DdrO ‐dependent repression of the promoter of a radiation‐induced gene was shown. These results demonstrate that IrrE is a metalloprotease and we propose that IrrE ‐mediated cleavage inactivates repressor protein DdrO , leading to transcriptional induction of various genes required for repair and survival after exposure of D einococcus to radiation.