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

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 fu...

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Bibliographic Details
Published in:Nucleic acids research 2007-05, Vol.35 (9), p.2861-2874
Main Authors: Nitharwal, Ram Gopal, Paul, Subhankar, Dar, Ashraf, Choudhury, Nirupam Roy, Soni, Rajesh K, Prusty, Dhaneswar, Sinha, Sukrat, Kashav, Tara, Mukhopadhyay, Gauranga, Chaudhuri, Tapan Kumar, Gourinath, Samudrala, Dhar, Suman Kumar
Format: Article
Language:English
Subjects:
Bacterial Proteins - chemistry
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
DnaB Helicases - chemistry
DnaB Helicases - genetics
DnaB Helicases - metabolism
Escherichia coli
Genetic Complementation Test
Helicobacter pylori
Helicobacter pylori - enzymology
Nucleic Acid Enzymes
Protein Structure, Tertiary
Sequence Deletion
Structural Homology, Protein
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Summary: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.
ISSN:0305-1048
1362-4962
DOI:10.1093/nar/gkm167