title: 'Modulation of the enzymatic activities of replicative helicase (DnaB) by interaction with Hp0897: a possible mechanism for helicase loading in Helicobacter pylori'.
abstract: DNA replication in Helicobacter pylori is initiated from a unique site (oriC) on its chromosome where several proteins assemble to form a functional replisome. The assembly of H. pylori replication machinery is similar to that of the model gram negative bacterium Escherichia coli except for the absence of DnaC needed to recruit the hexameric DnaB helicase at the replisome assembly site. In the absence of an obvious DnaC homologue inH. pylori, the question arises as to whether HpDnaB helicase is loaded at theHp-replication origin by itself or is assisted by other unidentified protein(s). A high-throughput yeast two-hybrid study has revealed two proteins of unknown functions (Hp0897 and Hp0340) that interact with HpDnaB. Here we demonstrate that Hp0897 interacts with HpDnaB helicase in vitro as well as in vivo Furthermore, the interaction stimulates the DNA binding activity of HpDnaB and modulates its adenosine triphosphate hydrolysis and helicase activities significantly. Prior complex formation of Hp0897 and HpDnaB enhances the binding/loading of DnaB onto DNA. Hp0897, along with HpDnaB, colocalizes with replication complex at initiation but does not move with the replisome during elongation. Together, these results suggest a possible role of Hp0897 in loading of HpDnaB at oriC.
authors.affiliation: Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi-110067, India.
authors.forename: Vijay
authors.initials: V
authors.lastname: Verma
authors.affiliation: Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi-110067, India.
authors.forename: Ajay
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi-110067, India Department of Cell and Molecular Biology, Uppsala University, Box 596, Uppsala-75124, Sweden.
authors.forename: Ram Gopal
authors.initials: RG
authors.lastname: Nitharwal
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata-700010, India.
authors.forename: Jawed
authors.initials: J
authors.lastname: Alam
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata-700010, India.
authors.forename: Asish Kumar
authors.initials: AK
authors.lastname: Mukhopadhyay
authors.affiliation: Department of Cell and Molecular Biology, Uppsala University, Box 596, Uppsala-75124, Sweden.
authors.forename: Santanu
authors.initials: S
authors.lastname: Dasgupta
authors.affiliation: Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi-110067, India skdhar2002@yahoo.co.in.
authors.forename: Suman Kumar
authors.initials: SK
authors.lastname: Dhar
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D053488:DnaB Helicases / Q000737:chemistry / Q000378:metabolism*; D016480:Helicobacter pylori / Q000201:enzymology* / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism; D011485:Protein Binding; D055503:Protein Multimerization; D000099272:Replisomes
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004259:DNA-Directed DNA Polymerase; D053488:DnaB Helicases; D009097:Multienzyme Complexes; D000099272:Replisomes