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Functional characterization of DnaB helicase and its modulation by single‐stranded DNA binding protein in Mycobacterium tuberculosis
Author(s) -
Zhang Hua,
Zhang Zhuanmei,
Yang Jian,
He ZhengGuo
Publication year - 2014
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.12703
Subject(s) - dnab helicase , helicase , biology , dna , mycobacterium tuberculosis , primase , escherichia coli , dna replication , microbiology and biotechnology , biochemistry , tuberculosis , gene , rna , medicine , reverse transcriptase , pathology
DnaB is important in the initiation and extension stages of DNA replication. Although DnaB has been studied in many bacterial species, its function in the devastating human pathogen Mycobacterium tuberculosis remains unclear. In this study, an intein‐deleted form of M. tuberculosis DnaB (MtbDnaB) was cloned, expressed and characterized. MtbDnaB exhibited strong 5′ to 3′ helicase and ATP ase activities, suggesting that MtbDnaB is a functional homolog of Escherichia coli DnaB. A physical interaction between Mtb SSB (single‐stranded binding protein of M. tuberculosis ) and MtbDnaB was further identified in vivo and in vitro . The Mtb SSB C‐terminal fragment was found to have a critical function in this interaction. Moreover, the helicase activity of MtbDnaB was stimulated by Mtb SSB at low concentrations and inhibited at high concentrations. An Mtb SSB mutant with decreased binding affinity for ss DNA can stimulate the helicase activity of MtbDnaB over a wider concentration range than wild‐type Mtb SSB . These results suggest that Mtb SSB assists in the loading of MtbDnaB on the DNA replication fork in M. tuberculosis .Structured digital abstract MtbSSB physically interacts with MtbDnaB by two hybrid ( View interaction ) MtbDnaB physically interacts with MtbSSB by cross-linking study ( View interaction ) MtbDnaB binds to MtbSSB by surface plasmon resonance ( View interaction )