TY - JOUR T1 - Direct binding of Cdt2 to PCNA is important for targeting the CRL4<sup>Cdt2</sup> E3 ligase activity to Cdt1 JF - Life Science Alliance JO - Life Sci. Alliance DO - 10.26508/lsa.201800238 VL - 1 IS - 6 SP - e201800238 AU - Akiyo Hayashi AU - Nickolaos Nikiforos Giakoumakis AU - Tatjana Heidebrecht AU - Takashi Ishii AU - Andreas Panagopoulos AU - Christophe Caillat AU - Michiyo Takahara AU - Richard G Hibbert AU - Naohiro Suenaga AU - Magda Stadnik-Spiewak AU - Tatsuro Takahashi AU - Yasushi Shiomi AU - Stavros Taraviras AU - Eleonore von Castelmur AU - Zoi Lygerou AU - Anastassis Perrakis AU - Hideo Nishitani Y1 - 2018/12/01 UR - https://www.life-science-alliance.org/content/1/6/e201800238.abstract N2 - The CRL4Cdt2 ubiquitin ligase complex is an essential regulator of cell-cycle progression and genome stability, ubiquitinating substrates such as p21, Set8, and Cdt1, via a display of substrate degrons on proliferating cell nuclear antigens (PCNAs). Here, we examine the hierarchy of the ligase and substrate recruitment kinetics onto PCNA at sites of DNA replication. We demonstrate that the C-terminal end of Cdt2 bears a PCNA interaction protein motif (PIP box, Cdt2PIP), which is necessary and sufficient for the binding of Cdt2 to PCNA. Cdt2PIP binds PCNA directly with high affinity, two orders of magnitude tighter than the PIP box of Cdt1. X-ray crystallographic structures of PCNA bound to Cdt2PIP and Cdt1PIP show that the peptides occupy all three binding sites of the trimeric PCNA ring. Mutating Cdt2PIP weakens the interaction with PCNA, rendering CRL4Cdt2 less effective in Cdt1 ubiquitination and leading to defects in Cdt1 degradation. The molecular mechanism we present suggests a new paradigm for bringing substrates to the CRL4-type ligase, where the substrate receptor and substrates bind to a common multivalent docking platform to enable subsequent ubiquitination. ER -