The C-terminus of Dpb2 is required for interaction with Pol2 and for cell viability

Nucleic Acids Res. 2012 Dec;40(22):11545-53. doi: 10.1093/nar/gks880. Epub 2012 Oct 2.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • DNA Polymerase II / chemistry
  • DNA Polymerase II / genetics*
  • DNA Polymerase II / metabolism*
  • Microbial Viability
  • Mutation
  • Protein Interaction Domains and Motifs
  • Protein Subunits / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism*

Substances

  • Protein Subunits
  • Saccharomyces cerevisiae Proteins
  • Dpb2 protein, S cerevisiae
  • DNA Polymerase II