title: DR2417, a hypothetical protein characterized as a novel β-CASP family nuclease in radiation resistant bacterium, Deinococcus radiodurans.
abstract: BACKGROUND
  Deinococcus radiodurans survives extreme doses of radiations contributed by efficient DNA repair pathways. DR2417 (DncA) was detected separately both in a pool of nucleotide binding proteins and multiprotein complex isolated from cells undergoing DNA repair.
  
  
  METHODS
  DR_2417m ORF was sequenced and amino acid sequence of DncA was search for structural similarities with other proteins and functional motifs. Recombinant DncA was characterized for its DNA metabolic functions in vitro and its role in radiation resistance.
  
  
  CONCLUSIONS
  Sequencing of DR_2417m did not show the reported frame shift at 996th nucleotide position of this gene. DncA showed similarities with β-CASP family nucleases. Recombinant protein acted efficiently on dsDNA and showed an Mn2+ dependent 3'→5' exonuclease and ssDNA/dsDNA junction endonuclease activities while a very low level activity on RNA. The DNase activity of this protein was inhibited in presence of ATP. Its transcription was induced upon γ radiation exposure and a reduction in its copy number resulted in reduced growth rate and loss of γ radiation resistance in Deinococcus.
  
  
  CONCLUSIONS
  Our results suggest that DncA was a novel nuclease of β CASP family having a strong dsDNA end processing activity and it seems to be an essential gene required for both growth and γ radiation resistance of this bacterium.
  
  
  CONCLUSIONS
  Traditionally DncA should have shown both DNase and RNase functions as other members of β CASP family nucleases. A strong DNase and poor RNase activity possibly made it functionally significant in the radioresistance of D. radiodurans, which would be worth investigating independently.
authors.affiliation: Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Anubrata D
authors.initials: AD
authors.lastname: Das
authors.forename: Hari S
authors.initials: HS
authors.lastname: Misra
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism* / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D034301:Deinococcus / Q000201:enzymology* / Q000528:radiation effects*; D005092:Exonucleases / Q000378:metabolism*; D005720:Gamma Rays; D011836:Radiation Tolerance; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011994:Recombinant Proteins; D005092:Exonucleases; C026919:nuclease beta