TY - JOUR
T1 - PCNA binding domains in all three subunits of yeast DNA polymerase δ modulate its function in DNA replication
AU - Acharya, Narottam
AU - Klassen, Roland
AU - Johnson, Robert
AU - Prakash, Louise
AU - Prakash, Satya
PY - 2011/11/1
Y1 - 2011/11/1
N2 - DNA polymerase δ (Polδ) plays an essential role in replication from yeast to humans. Polδ in Saccharomyces cerevisiae is comprised of three subunits, the catalytic subunit Pol3 and the accessory subunits Pol31 and Pol32. Yeast Polδ exhibits a very high processivity in synthesizing DNA with the proliferating cell nuclear antigen (PCNA) sliding clamp; however, it has remained unclear how Polδbinds PCNA to achieve its high processivity. Here we show that PCNA interacting protein (PIP) motifs in all three subunits contribute to PCNA-stimulated DNA synthesis by Polδ, and mutational inactivation of all three PIP motifs abrogates its ability to synthesize DNA with PCNA. Genetic analyses of mutations in these PIPs have revealed that in the absence of functional Pol32 PIP domain, PCNA binding by both the Pol3 and Pol31 subunits becomes essential for cell viability. Based on our biochemical and genetic studies we infer that yeast Polδ can simultaneously utilize all three PIP motifs during PCNA-dependent DNA synthesis, and suggest that Polδ binds the PCNA homotrimer via its three subunits. We consider the implications of these observations for Polδ's role in DNA replication.
AB - DNA polymerase δ (Polδ) plays an essential role in replication from yeast to humans. Polδ in Saccharomyces cerevisiae is comprised of three subunits, the catalytic subunit Pol3 and the accessory subunits Pol31 and Pol32. Yeast Polδ exhibits a very high processivity in synthesizing DNA with the proliferating cell nuclear antigen (PCNA) sliding clamp; however, it has remained unclear how Polδbinds PCNA to achieve its high processivity. Here we show that PCNA interacting protein (PIP) motifs in all three subunits contribute to PCNA-stimulated DNA synthesis by Polδ, and mutational inactivation of all three PIP motifs abrogates its ability to synthesize DNA with PCNA. Genetic analyses of mutations in these PIPs have revealed that in the absence of functional Pol32 PIP domain, PCNA binding by both the Pol3 and Pol31 subunits becomes essential for cell viability. Based on our biochemical and genetic studies we infer that yeast Polδ can simultaneously utilize all three PIP motifs during PCNA-dependent DNA synthesis, and suggest that Polδ binds the PCNA homotrimer via its three subunits. We consider the implications of these observations for Polδ's role in DNA replication.
UR - http://www.scopus.com/inward/record.url?scp=81055141516&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=81055141516&partnerID=8YFLogxK
U2 - 10.1073/pnas.1109981108
DO - 10.1073/pnas.1109981108
M3 - Article
C2 - 22003126
AN - SCOPUS:81055141516
SN - 0027-8424
VL - 108
SP - 17927
EP - 17932
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 44
ER -