Crystal structure of the human Polε B-subunit in complex with the C-terminal domain of the catalytic subunit

Andrey G. Baranovskiy, Jianyou Gu, Nigar D. Babayeva, Igor Kurinov, Youri I. Pavlov, Tahir H. Tahirov

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The eukaryotic B-family DNA polymerases include four members: Polα, Polδ, Polε, and Polζ, which share common architectural features, such as the exonuclease/polymerase and C-terminal domains (CTDs) of catalytic subunits bound to indispensable B-subunits, which serve as scaffolds that mediate interactions with other components of the replication machinery. Crystal structures for the B-subunits of Polα and Polδ/Polζ have been reported: the former within the primosome and separately with CTD and the latter with the N-terminal domain of the C-subunit. Here we present the crystal structure of the human Polε B-subunit (p59) in complex with CTD of the catalytic subunit (p261C). The structure revealed a well defined electron density for p261C and the phosphodiesterase and oligonucleotide/oligosaccharide-binding domains of p59. However, electron density was missing for the p59 N-terminal domain and for the linker connecting it to the phosphodiesterase domain. Similar to Polα, p261C of Polε contains a three-helix bundle in the middle and zinc-binding modules on each side. Intersubunit interactions involving 11 hydrogen bonds and numerous hydrophobic contacts account for stable complex formation with a buried surface area of 3094 Å2. Comparative structural analysis of p59 –p261C with the corresponding Polα complex revealed significant differences between the B-subunits and CTDs, as well as their interaction interfaces. The B-subunit of Polδ/Polζ also substantially differs from B-subunits of either Polα or Polε. This work provides a structural basis to explain biochemical and genetic data on the importance of B-subunit integrity in replisome function in vivo.

Original languageEnglish (US)
Pages (from-to)15717-15730
Number of pages14
JournalJournal of Biological Chemistry
Issue number38
StatePublished - Sep 22 2017

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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