Conservation of eubacterial replicases
The last 15 years of effort in understanding bacterial DNA replication and repair has identified that the donut shaped beta(2) sliding clamp is harnessed by very functionally different DNA polymerases throughout the lifecycle of the bacterial cell. Remarkably, the sites of binding of these polymerases, in most cases, appear to be the same shallow pocket on the beta dimer. In every case, binding of beta(2) by the polymerase enhances their processivity of DNA synthesis. This binding site is also the same point of interaction between beta(2) and the clamp loader complex, which binds beta(2), opens and places it onto the DNA strand and then vacates the site. beta(2) may also be involved in the initiation of DNA replication again via contact through this same site. While much of the research effort has focused on Escherichia coli and Bacillus subtilis, conservation of this complex system is becoming apparent in diverse bacteria.