title: Phosphorylation of Deinococcus radiodurans RecA Regulates Its Activity and May Contribute to Radioresistance.
abstract: Deinococcus radiodurans has a remarkable capacity to survive exposure to extreme levels of radiation that cause hundreds of DNA double strand breaks (DSBs). DSB repair in this bacterium depends on its recombinase A protein (DrRecA). DrRecA plays a pivotal role in both extended synthesis-dependent strand annealing and slow crossover events of DSB repair during the organism's recovery from DNA damage. The mechanisms that control DrRecA activity during the D. radiodurans response to γ radiation exposure are unknown. Here, we show that DrRecA undergoes phosphorylation at Tyr-77 and Thr-318 by a DNA damage-responsive serine threonine/tyrosine protein kinase (RqkA). Phosphorylation modifies the activity of DrRecA in several ways, including increasing its affinity for dsDNA and its preference for dATP over ATP. Strand exchange reactions catalyzed by phosphorylated versus unphosphorylated DrRecA also differ. In silico analysis of DrRecA structure support the idea that phosphorylation can modulate crucial functions of this protein. Collectively, our findings suggest that phosphorylation of DrRecA enables the recombinase to selectively use abundant dsDNA substrate present during post-irradiation recovery for efficient DSB repair, thereby promoting the extraordinary radioresistance of D. radiodurans.
authors.affiliation: From the Molecular Biology Division and.
authors.forename: Yogendra S
authors.initials: YS
authors.lastname: Rajpurohit
authors.affiliation: Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India and.
authors.forename: Subhash C
authors.initials: SC
authors.lastname: Bihani
authors.affiliation: the Division of Infectious Diseases and Howard Hughes Medical Institute, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Waldor
authors.affiliation: From the Molecular Biology Division and hsmisra@barc.gov.in.
authors.forename: Hari S
authors.initials: HS
authors.lastname: Misra
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D034301:Deinococcus / Q000201:enzymology* / Q000235:genetics; D010766:Phosphorylation; D011836:Radiation Tolerance; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D011938:Rec A Recombinases
keywords: DNA repair; Deinococcus; Ser/Thr protein kinase; cell cycle; microbiology; molecular genetics; protein phosphorylation; radioresistance; recombinase A