2. Academic Validation
  3. E3 ligase autoinhibition by C-degron mimicry maintains C-degron substrate fidelity

E3 ligase autoinhibition by C-degron mimicry maintains C-degron substrate fidelity

  • Mol Cell. 2023 Feb 10;S1097-2765(23)00042-4. doi: 10.1016/j.molcel.2023.01.019.
Daniel C Scott 1,  Moeko T King 2,  Kheewoong Baek 3,  Clifford T Gee 4,  Ravi Kalathur 5,  Jerry Li 6,  Nicholas Purser 6,  Amanda Nourse 5,  Sergio C Chai 4,  Sivaraja Vaithiyalingam 5,  Taosheng Chen 4,  Richard E Lee 4,  Stephen J Elledge 7,  Gary Kleiger 6,  Brenda A Schulman 8
Affiliations

Affiliations

  • 1 Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA. Electronic address: danny.scott@stjude.org.
  • 2 Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
  • 3 Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany.
  • 4 Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA.
  • 5 Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Protein Technologies Center, St. Jude Children's Research Hospital, Memphis, TN, USA.
  • 6 Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Las Vegas, NV, USA.
  • 7 Division of Genetics, Brigham and Women's Hospital, Howard Hughes Medical Institute, Department of Genetics, Harvard Medical School, Boston, MA, USA.
  • 8 Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany.
PMID: 36805027 DOI: 10.1016/j.molcel.2023.01.019
Abstract

E3 Ligase recruitment of proteins containing terminal destabilizing motifs (degrons) is emerging as a major form of regulation. How those E3s discriminate bona fide substrates from Other proteins with terminal degron-like sequences remains unclear. Here, we report that human KLHDC2, a CRL2 substrate receptor targeting C-terminal Gly-Gly degrons, is regulated through interconversion between two assemblies. In the self-inactivated homotetramer, KLHDC2's C-terminal Gly-Ser motif mimics a degron and engages the substrate-binding domain of another protomer. True substrates capture the monomeric CRL2KLHDC2, driving E3 activation by neddylation and subsequent substrate ubiquitylation. Non-substrates such as NEDD8 bind KLHDC2 with high affinity, but its slow on rate prevents productive association with CRL2KLHDC2. Without substrate, neddylated CRL2KLHDC2 assemblies are deactivated via distinct mechanisms: the monomer by deneddylation and the tetramer by auto-ubiquitylation. Thus, substrate specificity is amplified by KLHDC2 self-assembly acting like a molecular timer, where only bona fide substrates may bind before E3 Ligase inactivation.

Keywords

Autoinhibition; C-END degron; CUL2; Cullin-RING Ligase; E3; KLHDC10; KLHDC3; Kinetic proofreading; NEDD8; Targeted protein degradation; allostery; higher-order assembly; protein-protein interaction; ubiquitin.

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