Regulation of HLTF-mediated PCNA polyubiquitination by RFC and PCNA monoubiquitination levels determines choice of damage tolerance pathway.

摘要: DNA-damage tolerance protects cells via at least two sub-pathways regulated by proliferating cell nuclear antigen (PCNA) ubiquitination in eukaryotes: translesion DNA synthesis (TLS) and template switching (TS), which are stimulated mono- polyubiquitination, respectively. However, how choose between the pathways remains unclear. The regulation of ubiquitin ligases catalyzing such as helicase-like transcription factor (HLTF), could play a role choice pathway. Here, we demonstrate that ligase activity HLTF is double-stranded HIRAN domain-dependent recruitment to stalled primer ends. Replication C (RFC) PCNA located ends, however, suppress en bloc polyubiquitination complex, redirecting toward sequential chain elongation. When complex monoubiquitinated RAD6-RAD18, resulting moiety immediately polyubiquitinated coexisting HLTF, indicating coupling reaction polyubiquitination. By contrast, when was absence it not subsequently recruited unless all three-subunits were monoubiquitinated, uncoupling specifically occurs on three-subunit-monoubiquitinated PCNA. We discuss physiological relevance different modes TLS TS under conditions.