Answer: Unzips the DNA molecule
What is the role of the DNA helicase in the replication of DNA?

DnaB helicase is an enzyme in bacteria which opens the replication fork during DNA replication. Although the mechanism by which DnaB both couples ATP hydrolysis to translocation along DNA and denatures the duplex is unknown a change in the quaternary structure of the protein involving dimerisation of the N-terminal domain has been observed and may occur during the enzymatic cycle. Initially when …

DnaB helicase is an enzyme in bacteria which opens the replication fork during DNA replication. Although the mechanism by which DnaB both couples ATP hydrolysis to translocation along DNA and denatures the duplex is unknown a change in the quaternary structure of the protein involving dimerisation of the N-terminal domain has been observed and may occur during the enzymatic cycle. Initially when DnaB binds to dnaA it is associated with dnaC a negative regulator. After DnaC dissociates DnaB binds dnaG. The N-terminal has a multi-helical structure that forms an orthogonal bundle. The C-terminal domain contains an ATP-binding site and is therefore probably the site of ATP hydrolysis. In eukaryotes helicase function is provided by the MCM (Minichromosome maintenance) complex. 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.

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 dnaB and the second DNA strand is excluded. The binding of dNTPs causes a conformational change which allows the dnaB to translocate along the DNA thus mechanically forcing the separation …

In E. coli dnaB is ...

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