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Article Dans Une Revue PLoS ONE Année : 2018

Characterization of biochemical properties of an apurinic/apyrimidinic endonuclease from Helicobacter pylori

Aigerim Turgimbayeva
  • Fonction : Auteur
Sailau Abeldenov
  • Fonction : Auteur
Alexander Ishchenko
Yerlan Ramankulov
  • Fonction : Auteur
Murat Saparbaev
Bekbolat Khassenov
  • Fonction : Auteur
  • PersonId : 1056457

Résumé

Apurinic/apyrimidinic (AP) endonucleases play critical roles in the repair of abasic sites and strand breaks in DNA. Complete genome sequences of Helicobacter pylori reveal that this bacterial specie has a single AP endonuclease. An H. pylori homolog of Xth (HpXth) is a member of exonuclease III family, which is represented by Escherichia coli Xth. Currently, it remains unknown whether this single AP endonuclease has DNA repair activities similar to those of its counterpart in E. coli and other bacteria. We report that HpXth possesses efficient AP site cleavage, 3'-repair phosphodiesterase, and 3'-phosphatase activities but not the nucleotide incision repair function. Optimal reaction conditions for HpXth's AP endonu-clease activity are low ionic strength, high Mg 2+ concentration, pH in the range 7-8, and temperature 30˚C. The kinetic parameters measured under steady-state conditions showed that HpXth removes the AP site, 3'-blocking sugar-phosphate, and 3'-terminal phosphate in DNA strand breaks with good efficiency (k cat /K M = 1240, 44, and 5,4 μM-1 Ámin-1 , respectively), similar to that of E. coli Xth. As expected, the presence of HpXth protein in AP endo-nuclease-deficient E. coli xth nfo strain significantly reduced the sensitivity to an alkylating agent and H 2 O 2. Mutation of active site residue D144 in HpXth predicted to be essential for catalysis resulted in a complete loss of enzyme activities. Several important structural features of HpXth were uncovered by homology modeling and phylogenetic analysis. Our data show the DNA substrate specificity of H. pylori AP endonuclease and suggest that HpXth counteracts the genotoxic effects of DNA damage generated by endogenous and host-imposed factors.
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hal-02322329 , version 1 (21-10-2019)

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Aigerim Turgimbayeva, Sailau Abeldenov, Dmitry Zharkov, Alexander Ishchenko, Yerlan Ramankulov, et al.. Characterization of biochemical properties of an apurinic/apyrimidinic endonuclease from Helicobacter pylori. PLoS ONE, 2018, 13 (8), pp.e0202232. ⟨10.1371/journal.pone.0202232⟩. ⟨hal-02322329⟩
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