title: The ClpPX protease is required for radioresistance and regulates cell division after gamma-irradiation in Deinococcus radiodurans.
abstract: Protein degradation in bacteria is involved in diverse cellular responses to environmental stimuli and in removing potentially toxic damaged proteins or protein aggregates. ATP-dependent proteases play a key role in these processes. Here, we have individually inactivated all the ATP-dependent proteases belonging to the Clp or Lon families in Deinococcus radiodurans. The mutants were tested for survival after gamma-irradiation and for sensitivity to the tRNA analogue puromycin in order to assess the impact of each disruption on radioresistance, as well as on proteolysis of misfolded proteins. We found that inactivation of the ClpPX protease significantly decreased cell survival at elevated gamma-irradiation doses, while inactivation of Lon1 and Lon2 proteases reduced resistance to puromycin, suggesting that they play a role in eliminating damaged proteins. Mutants devoid of ClpPX protease displayed altered kinetics of DNA double-strand break repair and resumed cell division after an exceedingly long lag phase following completion of DNA repair. During this stasis period, most of the DeltaclpPX irradiated cells showed decondensed nucleoids and abnormal septa and some cells were devoid of DNA. We propose that the ClpPX protease is involved in the control of proper chromosome segregation and cell division in cells recovering from DNA damage.
authors.affiliation: Université Paris-Sud 11, CNRS UMR 8621, LRC CEA 42V, Institut de Génétique et Microbiologie, Bâtiment 409, F-91405 Orsay Cedex, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Servant
authors.forename: Edmond
authors.initials: E
authors.lastname: Jolivet
authors.forename: Esma
authors.initials: E
authors.lastname: Bentchikou
authors.forename: Samuel
authors.initials: S
authors.lastname: Mennecier
authors.forename: Adriana
authors.initials: A
authors.lastname: Bailone
authors.forename: Suzanne
authors.initials: S
authors.lastname: Sommer
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000502:physiology; D034301:Deinococcus / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects*; D049071:Endopeptidase Clp / Q000378:metabolism*; D005720:Gamma Rays; D017353:Gene Deletion; D050296:Microbial Viability / Q000187:drug effects*; D016254:Mutagenesis, Insertional; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011691:Puromycin / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D011500:Protein Synthesis Inhibitors; D011691:Puromycin; D049071:Endopeptidase Clp