title: Regulation of polymerase exchange between Poleta and Poldelta by monoubiquitination of PCNA and the movement of DNA polymerase holoenzyme.
abstract: To ensure efficient and timely replication of genomic DNA, organisms in all three kingdoms of life possess specialized translesion DNA synthesis (TLS) polymerases (Pols) that tolerate various types of DNA lesions. It has been proposed that an exchange between the replicative DNA Pol and the TLS Pol at the site of DNA damage enables lesion bypass to occur. However, to date the molecular mechanism underlying this process is not fully understood. In this study, we demonstrated in a reconstituted system that the exchange of Saccharomyces cerevisiae Poldelta with Poleta requires both the stalling of the holoenzyme and the monoubiquitination of proliferating cell nuclear antigen (PCNA). A moving Poldelta holoenzyme is refractory to the incoming Poleta. Furthermore, we showed that the Poleta C-terminal PCNA-interacting protein motif is required for the exchange process. We also demonstrated that the second exchange step to bring back Poldelta is prohibited when Lys-164 of PCNA is monoubiquitinated. Thus the removal of the ubiquitin moiety from PCNA is likely required for the reverse exchange step after the lesion bypass synthesis by Poleta.
authors.affiliation: Department of Chemistry, 414 Wartik Laboratory, Pennsylvania State University, University Park, PA 16802, USA. zzhuang@udel.edu
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Zhuang
authors.forename: Robert E
authors.initials: RE
authors.lastname: Johnson
authors.forename: Lajos
authors.initials: L
authors.lastname: Haracska
authors.forename: Louise
authors.initials: L
authors.lastname: Prakash
authors.forename: Satya
authors.initials: S
authors.lastname: Prakash
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Benkovic
mesh_terms: D004258:DNA Polymerase III / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D020035:Holoenzymes / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D054875:Ubiquitination; D000099270:Y-Family DNA Polymerases
chemical_list: D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D020035:Holoenzymes; D018809:Proliferating Cell Nuclear Antigen; D029701:Saccharomyces cerevisiae Proteins; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases