Phosphorylation of the p68 Subunit of Pol δ Acts as a Molecular Switch To Regulate Its Interaction with PCNA

• Published in: Biochemistry (Easton) 2012-01, Vol.51 (1), p.416-424
• Main Authors: Rahmeh, Amal A, Zhou, Yajing, Xie, Bin, Li, Hao, Lee, Ernest Y. C, Lee, Marietta Y. W. T
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs - genetics; Amino Acid Sequence; Aspartic Acid - genetics; Cyclic AMP-Dependent Protein Kinases - chemistry; Cyclic AMP-Dependent Protein Kinases - physiology; DNA Polymerase III - antagonists & inhibitors; DNA Polymerase III - chemistry; DNA Polymerase III - genetics; Down-Regulation - genetics; HeLa Cells; Humans; Molecular Mimicry - genetics; Molecular Sequence Data; Mutation; Phosphorylation - genetics; Proliferating Cell Nuclear Antigen - chemistry; Proliferating Cell Nuclear Antigen - genetics; Proliferating Cell Nuclear Antigen - metabolism; Protein Binding - genetics; Protein Processing, Post-Translational - genetics; Protein Subunits - antagonists & inhibitors; Protein Subunits - chemistry; Protein Subunits - genetics; Serine - genetics
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi201638e

DNA polymerase delta (Pol δ) is a central enzyme for eukaryotic DNA replication and repair. Pol δ is a complex of four subunits p125, p68, p50, and p12. The functional properties of Pol δ are largely determined by its interaction with its DNA sliding clamp PCNA (proliferating cellular nuclear antigen). The regulatory mechanisms that govern the association of Pol δ with PCNA are largely unknown. In this study, we identified S458, located in the PCNA-interacting protein (PIP-Box) motif of p68, as a phosphorylation site for PKA. Phosphomimetic mutation of S458 resulted in a decrease in p68 affinity for PCNA as well as the processivity of Pol δ. Our results suggest a role of phosphorylation of the PIP-motif of p68 as a molecular switch that dynamically regulates the functional properties of Pol δ.