title: The domain structure of Helicobacter pylori DnaB helicase: the N-terminal domain can be dispensable for helicase activity whereas the extreme C-terminal region is essential for its function.
abstract: Hexameric DnaB type replicative helicases are essential for DNA strand unwinding along with the direction of replication fork movement. These helicases in general contain an amino terminal domain and a carboxy terminal domain separated by a linker region. Due to the lack of crystal structure of a full-length DnaB like helicase, the domain structure and function of these types of helicases are not clear. We have reported recently that Helicobacter pylori DnaB helicase is a replicative helicase in vitro and it can bypass Escherichia coli DnaC activity in vivo. Using biochemical, biophysical and genetic complementation assays, here we show that though the N-terminal region of HpDnaB is required for conformational changes between C6 and C3 rotational symmetry, it is not essential for in vitro helicase activity and in vivo function of the protein. Instead, an extreme carboxy terminal region and an adjacent unique 34 amino acid insertion region were found to be essential for HpDnaB activity suggesting that these regions are important for proper folding and oligomerization of this protein. These results confer great potential in understanding the domain structures of DnaB type helicases and their related function.
authors: Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Ram Gopal
authors: RG
authors: Nitharwal
authors: Subhankar
authors: S
authors: Paul
authors: Ashraf
authors: A
authors: Dar
authors: Nirupam Roy
authors: NR
authors: Choudhury
authors: Rajesh K
authors: RK
authors: Soni
authors: Dhaneswar
authors: D
authors: Prusty
authors: Sukrat
authors: S
authors: Sinha
authors: Tara
authors: T
authors: Kashav
authors: Gauranga
authors: G
authors: Mukhopadhyay
authors: Tapan Kumar
authors: TK
authors: Chaudhuri
authors: Samudrala
authors: S
authors: Gourinath
authors: Suman Kumar
authors: SK
authors: Dhar
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053488:DnaB Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D016480:Helicobacter pylori / Q000201:enzymology*; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D040681:Structural Homology, Protein
chemical_list: D001426:Bacterial Proteins; C506730:dnaB protein, E coli; D053488:DnaB Helicases