Radiation response in Deinococcus deserti: IrrE is a metalloprotease that cleaves repressor protein DdrO. Issue 2 (18th September 2014)

• Record Type: Journal Article
• Authors: Ludanyi, Monika; Blanchard, Laurence; Dulermo, Rémi; Brandelet, Géraldine; Bellanger, Laurent; Pignol, David; Lemaire, David; de Groot, Arjan
• Is Part Of: Molecular microbiology. Volume 94:Issue 2(2014)
• Page Start: 434
• Page End: 449
• Publication Date: 2014-09-18
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12774
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p> <italic>D</italic> <italic>einococcus</italic> 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 <italic>recA</italic> and other DNA repair genes. Earlier studies indicated that IrrE could be a zinc peptidase, but proteolytic activity was not demonstrated. Here, using several <italic>in vivo</italic> and <italic>in vitro</italic> experiments, IrrE from <italic>D</italic><italic>einococcus deserti</italic> was found to interact with DdrO, a predicted regulator encoded by a radiation‐induced gene that is, like <italic>irrE</italic>, highly conserved in <italic>D</italic><italic>einococcus</italic>. Moreover, IrrE was found to cleave DdrO <italic>in vitro</italic> and when the proteins were coexpressed in <italic>E</italic><italic>scherichia coli</italic>. 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 <italic>D</italic><italic>. deserti</italic>, 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 <italic>D</italic><italic>einococcus</italic> to radiation.</p> </abstract>