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Updated: Dec 25, 2025

In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
The interaction between ubiquitin and yeast polymerase η C terminus does not require the UBZ domain
Phuong Thi Mai Duong1, Anh Thi Ngoc Bui2, Seong-Ok Kim1,3
1Department of Chemistry, KAIST, Daejeon, Korea.
Abstract:
Polymerase η (Polη) is one of the Y-family polymerases that is recruited by monoubiquitinated proliferating cell nuclear antigen (Ub-PCNA) to DNA damage sites during translesion synthesis (TLS). This interaction is mediated by an ubiquitin-binding zinc-finger (UBZ) domain and a PCNA-interacting protein (PIP) box in Polη, which binds to ubiquitin and PCNA, respectively. Here, we show that without the UBZ domain, the PIP box of yeast Polη has a novel binding function with ubiquitin. Furthermore, the UBZ domain and the PIP box share the same binding surfaces for ubiquitin. The interaction with ubiquitin via the PIP box stabilizes the Ub-PCNA/Polη complex. Moreover, the PIP residues I624 and L625 contribute to Polη function in TLS in vivo.
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