RT Journal Article SR Electronic T1 Direct binding of Cdt2 to PCNA is important for targeting the CRL4Cdt2 E3 ligase activity to Cdt1 JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e201800238 DO 10.26508/lsa.201800238 VO 1 IS 6 A1 Akiyo Hayashi A1 Nickolaos Nikiforos Giakoumakis A1 Tatjana Heidebrecht A1 Takashi Ishii A1 Andreas Panagopoulos A1 Christophe Caillat A1 Michiyo Takahara A1 Richard G Hibbert A1 Naohiro Suenaga A1 Magda Stadnik-Spiewak A1 Tatsuro Takahashi A1 Yasushi Shiomi A1 Stavros Taraviras A1 Eleonore von Castelmur A1 Zoi Lygerou A1 Anastassis Perrakis A1 Hideo Nishitani YR 2018 UL https://www.life-science-alliance.org/content/1/6/e201800238.abstract AB 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.