Expanding the physiological role of the hexameric DnaB helicase

The hexameric DnaB protein is the Escherichia coli primary replicative helicase. However, recent studies indicate that this enzyme is capable of driving branch migration of a Holliday junction, acting more like an ATP-driven pump than a helicase. This offers an attractive possibility that the protein is directly involved in DNA recombination in vivo. Thus, the physiological role of the DnaB protein in DNA metabolism, and its modes of action, might be more complex than previously thought.