TAILIEUCHUNG - Báo cáo khoa học: Helicobacter pylori single-stranded DNA binding protein – functional characterization and modulation of H. pylori DnaB helicase activity

Helicobacter pylori, an important bacterial pathogen, causes gastric ulcer and gastric adenocarcinoma in humans. The fundamentals of basic biology such as DNA replication are poorly understood in this pathogen. In the present study, we report the cloning and functional characterization of the single-stranded DNA (ssDNA) binding protein from H. pylori. | ỊFEBS Journal Helicobacter pylori single-stranded DNA binding protein - functional characterization and modulation of H. pylori DnaB helicase activity Atul Sharma1 Ram G. Nitharwal1 Bhupender Singh2 Ashraf Dar1 Santanu Dasgupta2 and Suman K. Dhar1 1 SpecialCentre for Molecular Medicine JawaharlalNehru University New Delhi India 2 Department of Celland Molecular Biology Uppsala University BiomedicalCenter Sweden Keywords DNA replication helicase Helicobacter pylori replication foci single-stranded DNA binding protein Correspondence S. K. Dhar Special Centre for Molecular Medicine JNU New Delhi 110067 India Fax 91 11 26741781 Tel 91 11 26742572 E-mail skdhar2002@ These authors contributed equally to this work Received 7 October 2008 revised 10 November 2008 accepted 13 November 2008 doi Helicobacter pylori an important bacterial pathogen causes gastric ulcer and gastric adenocarcinoma in humans. The fundamentals of basic biology such as DNA replication are poorly understood in this pathogen. In the present study we report the cloning and functional characterization of the single-stranded DNA ssDNA binding protein from H. pylori. The N-ter-minal DNA binding domain shows significant homology with E. coli single-stranded DNA binding protein SSB whereas the C-terminal domain shows less homology. The overall DNA-binding activity and tetra-merization properties however remain unaffected. In in vitro experiments with purified proteins H. pylori Hp SSB bound specifically to ssDNA and modulated the enzymatic ATPase and helicase activity of HpDnaB helicase. HpSSB and HpDnaB proteins were co-localized in sharp distinct foci in exponentially growing H. pylori cells whereas both were spread over large areas in its dormant coccoid form suggesting the absence of active replication forks in the latter. These results confirm the multiple roles of SSB during DNA replication and provide evidence for altered replicative metabolism in the .

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