The DNA polymerase III holoenzyme contains γ and is not a trimeric polymerase.

ABSTRACT: There is widespread agreement that the clamp loader of the Escherichia coli replicase has the composition DnaX3δδ'χψ. Two DnaX proteins exist in E. coli, full length τ and a truncated γ that is created by ribosomal frameshifting. τ binds DNA polymerase III tightly; γ does not. There is a controversy as to whether or not DNA polymerase III holoenzyme (Pol III HE) contains γ. A three-τ form of Pol III HE would contain three Pol IIIs. Proponents of the three-τ hypothesis have claimed that γ found in Pol III HE might be a proteolysis product of τ. To resolve this controversy, we constructed a strain that expressed only τ from a mutated chromosomal dnaX. γ containing a C-terminal biotinylation tag (γ-C(tag)) was provided in trans at physiological levels from a plasmid. A 2000-fold purification

SUBMITTER: Dohrmann PR 

PROVIDER: S-EPMC4756838 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature