title: The Deinococcus radiodurans SMC protein is dispensable for cell viability yet plays a role in DNA folding.
abstract: Deinococcus radiodurans contains a highly condensed nucleoid that remains to be unaltered following the exposure to high doses of gamma-irradiation. Proteins belonging to the structural maintenance of chromosome protein (SMC) family are present in all organisms and were shown to be involved in chromosome condensation, pairing, and/or segregation. Here, we have inactivated the smc gene in the radioresistant bacterium D. radiodurans, and, unexpectedly, found that smc null mutants showed no discernible phenotype except an increased sensitivity to gyrase inhibitors suggesting a role of SMC in DNA folding. A defect in the SMC-like SbcC protein exacerbated the sensitivity to gyrase inhibitors of cells devoid of SMC. We also showed that the D. radiodurans SMC protein forms discrete foci at the periphery of the nucleoid suggesting that SMC could locally condense DNA. The phenotype of smc null mutant leads us to speculate that other, not yet identified, proteins drive the compact organization of the D. radiodurans nucleoid.
authors.affiliation: Univ Paris-Sud, CNRS UMR8621, CEA LRC42V, Institut de Génétique et Microbiologie, Bâtiment 409, 91405, Orsay Cedex, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Bouthier de la Tour
authors.forename: Magali
authors.initials: M
authors.lastname: Toueille
authors.forename: Edmond
authors.initials: E
authors.lastname: Jolivet
authors.forename: Hong-Ha
authors.initials: HH
authors.lastname: Nguyen
authors.forename: Pascale
authors.initials: P
authors.lastname: Servant
authors.forename: Françoise
authors.initials: F
authors.lastname: Vannier
authors.forename: Suzanne
authors.initials: S
authors.lastname: Sommer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry* / Q000235:genetics; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics; D034301:Deinococcus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D005798:Genes, Bacterial; D009154:Mutation; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000737:chemistry / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D004269:DNA, Bacterial; D004278:DNA, Superhelical; C118650:SMC protein, Bacteria; C061563:SbcC protein, Bacteria; D003851:Deoxyribonucleases