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PDBsum entry 3gxv
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Hydrolase/replication
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PDB id
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3gxv
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References listed in PDB file
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Key reference
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Title
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Three-Dimensional structure of n-Terminal domain of dnab helicase and helicase-Primase interactions in helicobacter pylori.
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Authors
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T.Kashav,
R.Nitharwal,
S.A.Abdulrehman,
A.Gabdoulkhakov,
W.Saenger,
S.K.Dhar,
S.Gourinath.
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Ref.
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Plos One, 2009,
4,
e7515.
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PubMed id
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Abstract
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Replication initiation is a crucial step in genome duplication and homohexameric
DnaB helicase plays a central role in the replication initiation process by
unwinding the duplex DNA and interacting with several other proteins during the
process of replication. N-terminal domain of DnaB is critical for helicase
activity and for DnaG primase interactions. We present here the crystal
structure of the N-terminal domain (NTD) of H. pylori DnaB (HpDnaB) helicase at
2.2 A resolution and compare the structural differences among helicases and
correlate with the functional differences. The structural details of NTD suggest
that the linker region between NTD and C-terminal helicase domain plays a vital
role in accurate assembly of NTD dimers. The sequence analysis of the linker
regions from several helicases reveals that they should form four helix bundles.
We also report the characterization of H. pylori DnaG primase and study the
helicase-primase interactions, where HpDnaG primase stimulates DNA unwinding
activity of HpDnaB suggesting presence of helicase-primase cohort at the
replication fork. The protein-protein interaction study of C-terminal domain of
primase and different deletion constructs of helicase suggests that linker is
essential for proper conformation of NTD to interact strongly with HpDnaG. The
surface charge distribution on the primase binding surface of NTDs of various
helicases suggests that DnaB-DnaG interaction and stability of the complex is
most probably charge dependent. Structure of the linker and helicase-primase
interactions indicate that HpDnaB differs greatly from E.coli DnaB despite both
belong to gram negative bacteria.
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