DNA and RNA-DNA annealing activity associated with the τ subunit of the Escherichia coil DNA polymerase III holoenzyme

Abstract

The DNA polymerase III (pol III)holoenzyme is the 10 subunit replicase of Escherichia coli. The 71 kDaτ subunit, encoded by dnaX, dimerizes the core polymerase (αεθ) to form pol III' [(αεθ)2τ2]. τ is also a single-stranded DNA-dependent ATPase and can substitute for the γ subunit during initiation complex formation. We show here that τ also possessesa DNA-DNA and RNA-DNA annealing activity that is stimulated by Mg2+ but neither requires ATP nor is inhibited by non-hydrolyzable ATP analogs. This suggests the τ may act to stabilize the primer-template interaction during DNA replication. © 1995 Oxford University Press.