Document Detail


Characterization of an ATP-regulated DNA-processing enzyme and thermotolerant phosphoesterase in the radioresistant bacterium Deinococcus radiodurans.
MedLine Citation:
PMID:  20658964     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A multiprotein DNA-processing complex identified from Deinococcus radiodurans exhibits uncharacterized ATP-sensitive nuclease functions. DR0505 was one of the 24 polypeptides identified from the complex. It contains two 5' nucleotidase motifs, one is at the C-terminal end of the N-terminal CPDD (calcineurin phosphodiesterase domain), with the second at the C-terminal end of the protein. Recombinant DR0505 showed both phosphomonoesterase and phosphodiesterase activities with chromogenic substrates, showing higher affinity for bis-(p-nitrophenyl) phosphate than for p-nitrophenyl phosphate. The enzyme exhibited pH optima ranging from 8.0 to 9.0 and metal-ion-dependent thermotolerance of esterase functions. Both mono- and di-esterase activities were stable at temperatures up to 50 °C in the presence of Mg2+, whereas monoesterase activity was observed at temperatures up to 80 °C in the presence of Mn2+ and up to 50 °C with Ca2+. The purified enzyme showed 5' nucleotidase activity on a wide range of natural mononucleotides including cyclic mononucleotides and 8-oxo-GMP. DR0505 showed a nearly 7-fold higher activity on ADP than AMP, but this activity was inhibited with ATP. Interestingly, DR0505 also showed single-stranded endonuclease and 3'→5' exonuclease activities on both single-stranded and double-stranded DNA-substrates. Unlike for the exonuclease activity, the single-stranded endonuclease activities observed on stem-loop substrates and at the single strand-double-strand junction in forked-hairpin substrates were not inhibited with ATP. These results suggested that DR0505 is an ATP-regulated DNA-processing enzyme and a thermotolerant esterase in vitro. We therefore suggest possible roles of this enzyme in nucleotide recycling and DNA processing, which is required for efficient double-strand break repair and the high radiation tolerance observed in D. radiodurans.
Authors:
Swathi Kota; C Vijaya Kumar; Hari S Misra
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  431     ISSN:  1470-8728     ISO Abbreviation:  Biochem. J.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-09-14     Completed Date:  2010-11-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  England    
Other Details:
Languages:  eng     Pagination:  149-57     Citation Subset:  IM    
Affiliation:
Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
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MeSH Terms
Descriptor/Qualifier:
Adenosine Triphosphate / metabolism
Bacterial Proteins / chemistry,  metabolism*
DNA Repair
DNA Repair Enzymes / chemistry,  metabolism*
DNA, Bacterial / chemistry,  metabolism*
DNA-Binding Proteins / chemistry,  metabolism
Deinococcus / enzymology*,  metabolism
Gamma Rays
Nucleotidases / chemistry,  metabolism*
Radiation Tolerance
Chemical
Reg. No./Substance:
0/Bacterial Proteins; 0/DNA, Bacterial; 0/DNA-Binding Proteins; 56-65-5/Adenosine Triphosphate; EC 3.1.3.-/Nucleotidases; EC 6.5.1.-/DNA Repair Enzymes

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