Hypothesis: bacterial clamp loader ATPase activation through DNA-dependent repositioning of the catalytic base and of a trans-acting catalytic threonine.

ABSTRACT: The prokaryotic DNA polymerase III clamp loader complex loads the beta clamp onto DNA to link the replication complex to DNA during processive synthesis and unloads it again once synthesis is complete. This minimal complex consists of one delta, one delta' and three gamma subunits, all of which possess an AAA+ module--though only the gamma subunit exhibits ATPase activity. Here clues to underlying clamp loader mechanisms are obtained through Bayesian inference of various categories of selective constraints imposed on the gamma and delta' subunits. It is proposed that a conserved histidine is ionized via electron transfer involving structurally adjacent residues within the sensor 1 region of gamma's AAA+ module. The resultant positive charge on this histidine inhibits ATPase activity by dra

SUBMITTER: Neuwald AF 

PROVIDER: S-EPMC1636414 | biostudies-literature | 2006

REPOSITORIES: biostudies-literature