Involvement of Pso2 in Okazaki fragment processing

Abstract

The yeast Pso2 is known as an interstrand crosslink (ICL) repair protein which has a 5’ exonuclease activity and hairpin structure specific endonuclease activity. In this report, Pso2 is identified as a multicopy suppressor of dna2Δ405N mutant. Both nuclease deficient Pso2 and N-terminal region of Pso2 devoid of nuclease domain could suppress dna2Δ405N mutant though the nuclease activity of Pso2 in ICL repair is essential. We investigated the interaction between Pso2 and Okazaki fragment processing proteins. We showed that Pso2 stimulated the flap endonu-clease activity of Fen1 and this is most likely through their physical interaction. Pso2 also stimulated the endonuclease activity of Dna2. These findings indicate that Pso2 is involved in Okazaki fragment processing.