title: The C-terminus of Dpb2 is required for interaction with Pol2 and for cell viability.
abstract: DNA polymerase ε (Pol ε) participates in the synthesis of the leading strand during DNA replication in Saccharomyces cerevisiae. Pol ε comprises four subunits: the catalytic subunit, Pol2, and three accessory subunits, Dpb2, Dpb3 and Dpb4. DPB2 is an essential gene with unclear function. A genetic screen was performed in S. cerevisiae to isolate lethal mutations in DPB2. The dpb2-200 allele carried two mutations within the last 13 codons of the open reading frame, one of which resulted in a six amino acid truncation. This truncated Dpb2 subunit was co-expressed with Pol2, Dpb3 and Dpb4 in S. cerevisiae, but this Dpb2 variant did not co-purify with the other Pol ε subunits. This resulted in the purification of a Pol2/Dpb3/Dpb4 complex that possessed high specific activity and high processivity and holoenzyme assays with PCNA, RFC and RPA on a single-primed circular template did not reveal any defects in replication efficiency. In conclusion, the lack of Dpb2 did not appear to have a negative effect on Pol ε activity. Thus, the C-terminal motif of Dpb2 that we have identified may instead be required for Dpb2 to fulfill an essential structural role at the replication origin or at the replication fork.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Isoz
authors.forename: Ulf
authors.initials: U
authors.lastname: Persson
authors.forename: Kirill
authors.initials: K
authors.lastname: Volkov
authors.forename: Erik
authors.initials: E
authors.lastname: Johansson
mesh_terms: D000483:Alleles; D004257:DNA Polymerase II / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D050296:Microbial Viability; D009154:Mutation; D054730:Protein Interaction Domains and Motifs; D021122:Protein Subunits / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C529202:Dpb2 protein, S cerevisiae; D004257:DNA Polymerase II