title: The essential histone-like protein HU plays a major role in Deinococcus radiodurans nucleoid compaction.
abstract: The nucleoid of radioresistant bacteria, including D. radiodurans, adopts a highly condensed structure that remains unaltered after exposure to high doses of irradiation. This structure may contribute to radioresistance by preventing the dispersion of DNA fragments generated by irradiation. In this report, we focused our study on the role of HU protein, a nucleoid-associated protein referred to as a histone-like protein, in the nucleoid compaction of D. radiodurans. We demonstrate, using a new system allowing conditional gene expression, that HU is essential for viability in D. radiodurans. Using a tagged HU protein and immunofluorescence microscopy, we show that HU protein localizes all over the nucleoid and that when HU is expressed from a thermosensitive plasmid, its progressive depletion at the non-permissive temperature generates decondensation of DNA before fractionation of the nucleoid into several entities and subsequent cell lysis. We also tested the effect of the absence of Dps, a protein also involved in nucleoid structure. In contrast to the drastic effect of HU depletion, no change in nucleoid morphology and cell viability was observed in dps mutants compared with the wild-type, reinforcing the major role of HU in nucleoid organization and DNA compaction in D. radiodurans.
authors: Univ. Paris-Sud 11, CNRS UMR 8621, LRC CEA 42V, Institut de Génétique et Microbiologie, Bâtiment 409, Université Paris-Sud, F-91405 Orsay Cedex, France.
authors: Hong Ha
authors: HH
authors: Nguyen
authors: Claire Bouthier
authors: CB
authors: de la Tour
authors: Magali
authors: M
authors: Toueille
authors: Françoise
authors: F
authors: Vannier
authors: Suzanne
authors: S
authors: Sommer
authors: Pascale
authors: P
authors: Servant
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D034301:Deinococcus / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D020043:Genes, Essential; D050296:Microbial Viability; D010957:Plasmids; D017384:Sequence Deletion; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C040330:histone-like protein HU, bacteria