The interaction between ubiquitin and yeast polymerase η C terminus does not require the UBZ domain

Abstract

Edited by Claus AzzalinPolymerase g (Polg) 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 Polg, which binds to ubiquitin and PCNA, respectively. Here, we show that without the UBZ domain, the PIP box of yeast Polg 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/Polg complex. Moreover, the PIP residues I624 and L625 contribute to Polg function in TLS in vivo.

Photo-activatable Ub-PCNA probes reveal new structural features of the Saccharomyces cerevisiae Polη/PCNA complex

“…The PIP box is well characterized for Polη’s interaction with PCNA ( 5 , 26 , 49 ). A recent NMR study suggested that the PIP box in yeast Polη also contributes to its interaction with Ub ( 50 ).…”