title: A Small Molecule That Switches a Ubiquitin Ligase From a Processive to a Distributive Enzymatic Mechanism.
abstract: E3 ligases are genetically implicated in many human diseases, yet E3 enzyme mechanisms are not fully understood, and there is a strong need for pharmacological probes of E3s. We report the discovery that the HECT E3 Nedd4-1 is a processive enzyme and that disruption of its processivity by biochemical mutations or small molecules switches Nedd4-1 from a processive to a distributive mechanism of polyubiquitin chain synthesis. Furthermore, we discovered and structurally characterized the first covalent inhibitor of Nedd4-1, which switches Nedd4-1 from a processive to a distributive mechanism. To visualize the binding mode of the Nedd4-1 inhibitor, we used X-ray crystallography and solved the first structure of a Nedd4-1 family ligase bound to an inhibitor. Importantly, our study shows that processive Nedd4-1, but not the distributive Nedd4-1:inhibitor complex, is able to synthesize polyubiquitin chains on the substrate in the presence of the deubiquitinating enzyme USP8. Therefore, inhibition of E3 ligase processivity is a viable strategy to design E3 inhibitors. Our study provides fundamental insights into the HECT E3 mechanism and uncovers a novel class of HECT E3 inhibitors.
authors.affiliation: Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Department of Chemistry, Department of Molecular Biosciences, Northwestern University , Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Kathman
authors.affiliation: Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Department of Chemistry, Department of Molecular Biosciences, Northwestern University , Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Span
authors.affiliation: Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Department of Chemistry, Department of Molecular Biosciences, Northwestern University , Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Smith
authors.affiliation: Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Department of Chemistry, Department of Molecular Biosciences, Northwestern University , Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Ziyang
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Department of Chemistry, Department of Molecular Biosciences, Northwestern University , Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Zhan
authors.affiliation: Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Department of Chemistry, Department of Molecular Biosciences, Northwestern University , Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Amy C
authors.initials: AC
authors.lastname: Rosenzweig
authors.affiliation: Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Department of Chemistry, Department of Molecular Biosciences, Northwestern University , Silverman Hall, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Statsyuk
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D056827:Endosomal Sorting Complexes Required for Transport / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008958:Models, Molecular; D000075702:Nedd4 Ubiquitin Protein Ligases; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D056827:Endosomal Sorting Complexes Required for Transport; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; C480733:SOSTDC1 protein, human; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; D044767:Ubiquitin-Protein Ligases