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DnaB helicase is an enzyme in bacteria which opens the replication fork during DNA replication. Initially when DnaB binds to DnaA, it is associated with DnaC, a negative regulator. After DnaC dissociates, DnaB binds DnaG.
In eukaryotes, helicase function is provided by the T antigen.
The DnaB helicase is the product of the dnaB gene. The helicase enzyme that is produced is a hexamer in E. coli, as well as in many other bacteria. The energy for DnaB activity is provided by NTP hydrolysis. Mechanical energy moves the DnaB into the replication fork, physically splitting it in half
E. coli DnaB
In E. coli, DnaB is a hexameric protein of six 471 residue subunits, which form a ring-shaped structure with threefold symmetry. During DNA replication, the lagging strand of DNA binds in the central channel of DNA, and the second DNA strand is excluded. The binding of NTPs causes a conformational change which allows the DnaB to translocate along the DNA, thus mechanically forcing the separation of the DNA strands.
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