Bacterial Helicases

DnaB is the primary replicative helicase in Escherichia coli and is responsible for unwinding the DNA duplex ahead of the replication fork so that the two strands can be replicated (1). It is a hexameric protein that unwinds DNA in an ATP-dependant manner by translocating along the single-stranded DNA in the 5’ – 3’ direction. The C-terminal domain contains an ATP-binding site. Two DnaB molecules travel in opposite directions along the two DNA strands unwinding the helix and creating two replication forks. DnaB helicase interacts with a number of proteins involved in replication and the principle step in the initiation of replication is the loading of DNA onto DnaB helicase.

The essential role of DnaBs amongst bacterial genomes as well as the structural divergence from their eukaryotic counterparts make bacterial  DnaBs ideal targets for antibiotic development (2).

References

(1) West SC. DNA helicases: new breeds of translocating motors and molecular pumps. Cell. 1996, 26;86(2):177-80.

(2) Griep MA, Blood S, Larson MA, Koepsell SA, Hinrichs SH. Myricetin inhibits Escherichia coli DnaB helicase but not primase. Bioorganic & medicinal chemistry. 2007, 15;15(22):7203-8.