A multifunctional DNA polymerase I involves in the maturation of Okazaki fragments during the lagging-strand DNA synthesis inHelicobacter pylori

Helicobacter pyloriis the most infectious human pathogen that causes gastritis, peptic ulcers and stomach cancer.H. pyloriDNA polymerase I (HpPol I) is found to be essential for the viability ofH. pylori, but its intrinsic property and attribution to theH. pyloriDNA replication remain unclear. HpPol I contains a 5 '-> 3 ' exonuclease (5 '-Exo) and DNA polymerase (Pol) domain, respectively, but lacks a 3 '-> 5 ' exonuclease, or error proofreading activity. In this study, we characterized the 5 '-Exo and Pol functions of HpPol I and found that HpPol I is a multifunctional protein displaying DNA nick translation, strand-displacement synthesis, RNase H-like, structure-specific endonuclease and exonuclease activities. In thein vitroDNA replication assay, we further demonstrated that the 5 '-Exo and Pol domains of HpPol I can cooperate to fill in the DNA gap, remove the unwanted RNA primer from a RNA/DNA hybrid and create a ligatable nick for the DNA ligase A ofH. pylorito restore the normal duplex DNA. Altogether, our study suggests that the two catalytic domains of HpPol I may synergistically play an important role in the maturation of Okazaki fragments during the lagging-strand DNA synthesis inH. pylori. Like the functions of DNA polymerase I inEscherichia coli, HpPol I may involve in both DNA replication and repair inH. pylori.

Automated summary

Helicobacter pylori is a highly infectious human pathogen causing various diseases. HpPol I, an essential protein for the viability of H. pylori, has multiple functions including DNA nick translation, strand-displacement synthesis, and exonuclease activities. The two catalytic domains of HpPol I may play a crucial role in DNA replication and repair in H. pylori.