Precise limits of the N-terminal domain of DnaB helicase determined by NMR spectroscopy.

Two separate N-terminal fragments of the 470-amino-acid Escherichia coli DnaB helicase, comprising residues 1-142 and 1-161, were expressed in E. coli. The proteins were extracted in a soluble fraction, purified, and characterised physically.

A structural model for the Escherichia coli DnaB helicase based on electron microscopy data.

The DnaB protein is the major replicative DNA helicase in Escherichia coli. It hydrolyzes ATP to promote its translocation in the 5' to 3' direction on single-stranded DNA templates, facilitating the separation of strands of duplex DNA in its path. This places it on the lagging strands at replication forks during chromosomal DNA replication.