title: Dual negative regulatory mechanisms of RecX on RecA functions in radiation resistance, DNA recombination and consequent genome instability in Deinococcus radiodurans.
abstract: RecA protein plays a central role in homologous recombination and DNA repair. RecX, a gene directly downstream in Escherichia coli and some other bacterial species, down regulates it. However, the precise mechanism of regulation of RecA by RecX is not known. In order to study the function of RecX in the highly radioresistant bacterium Deinococcus radiodurans, null and overexpression strains were constructed. Our data demonstrates that RecX represses radiation resistance, DNA recombination and consequent genome instability in the stationary phase bacteria. Further biochemical analyses reveal that RecX not only down regulates recA transcription, but also directly inhibits RecA activities in vitro. These data suggests a dual negative regulatory control of RecX on RecA functions in D. radiodurans.
authors.affiliation: Institute of Nuclear-Agricultural Sciences, Zhejiang University, 310029 Hangzhou, China.
authors.forename: Duohong
authors.initials: D
authors.lastname: Sheng
authors.forename: Ren
authors.initials: R
authors.lastname: Liu
authors.forename: Zhenjian
authors.initials: Z
authors.lastname: Xu
authors.forename: Purnima
authors.initials: P
authors.lastname: Singh
authors.forename: Binghui
authors.initials: B
authors.lastname: Shen
authors.forename: Yuejin
authors.initials: Y
authors.lastname: Hua
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002470:Cell Survival / Q000528:radiation effects; D002876:Chromosomes, Bacterial / Q000235:genetics; D004260:DNA Repair; D004269:DNA, Bacterial; D034301:Deinococcus / Q000166:cytology / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D015536:Down-Regulation; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000378:metabolism; D005720:Gamma Rays; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects*; D042822:Genomic Instability / Q000528:radiation effects*; D010957:Plasmids / Q000235:genetics / Q000302:isolation & purification; D011836:Radiation Tolerance; D011938:Rec A Recombinases / Q000037:antagonists & inhibitors*; D011995:Recombination, Genetic; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C430523:RecX protein, Xanthomonas campestris; D011938:Rec A Recombinases; D001616:beta-Galactosidase; D000251:Adenosine Triphosphatases