Dual mode of interaction of DNA polymerase ϵ with proliferating cell nuclear antigen in primer binding and DNA synthesis

Abstract

Proliferating cell nuclear antigen can interact with DNA polymerase ϵ on linear DNA templates, even in the absence of other auxiliary factors (replication factor C, replication protein A), and thereby stimulate its primer recognition and DNA synthesis. Using four characterized mutants of proliferating cell nuclear antigen containing three or four alanine residue substitutions on the C-terminal side and the back side of the trimer, we have tested the kinetics of primer binding and nucleotide incorporation by DNA polymerase ϵ in different assays. In contrast with what has been found in interaction studies between DNA polymerase δ and proliferating cell nuclear antigen, our data suggested that stimulation of DNA polymerase ϵ primer binding involves interactions with both the C-terminal side and the back side of proliferating cell nuclear antigen. However, for stimulation of DNA polymerase ϵ DNA synthesis, exclusively the C-terminal side appears to be sufficient. The significance of this dual interaction is discussed with reference to the physiological roles of DNA polymerase ϵ and its interaction with the clamp proliferating cell nuclear antigen.