Anubrata D Das

Publications (2)7.72 Total impact

• Article: DR2417, a hypothetical protein characterized as a novel β-CASP family nuclease in radiation resistant bacterium, Deinococcus radiodurans.

  Anubrata D Das, Hari S Misra
  [show abstract] [hide abstract]
  ABSTRACT: 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. 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. 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. 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. 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.
  Biochimica et Biophysica Acta 03/2012; 1820(7):1052-61. · 4.66 Impact Factor
• Article: Characterization of DRA0282 from Deinococcus radiodurans for its role in bacterial resistance to DNA damage.

  Anubrata D Das, Hari S Misra
  [show abstract] [hide abstract]
  ABSTRACT: DRA0282, a hypothetical protein, was found in a pool of nucleotide-binding proteins in Deinococcus radiodurans cells recovering from gamma radiation stress. This pool exhibited an unusual inhibition of nuclease activity by ATP. The N terminus of DRA0282 showed similarity to human Ku80 homologues, while the C terminus showed no similarities to known proteins. The recombinant protein required Mn(2+) for its interaction with DNA and protected dsDNA from exonuclease III degradation. The binding of the protein to supercoiled DNA with a K(d) of ~2.93 nM was nearly 20-fold stronger than its binding to ssDNA and nearly 67-fold stronger than its binding to linear dsDNA. Escherichia coli cells expressing DRA0282 showed a RecA-dependent enhancement of UV and gamma radiation tolerance. The ΔdrA0282 mutant of D. radiodurans showed a dose-dependent response to gamma radiation. At 14 kGy, the ΔdrA0282 mutant showed nearly 10-fold less survival, while at this dose both pprA : : catΔdrA0282 and pprA : : cat mutants were nearly 100-fold more sensitive than the wild-type. These results suggested that DRA0282 is a DNA-binding protein with a preference for superhelical DNA, and that it plays a role in bacterial resistance to DNA damage through a pathway in which PprA perhaps plays a dominant role in D. radiodurans.
  Microbiology 04/2011; 157(Pt 8):2196-205. · 3.06 Impact Factor