title: A conformational switch regulates the ubiquitin ligase HUWE1.
abstract: The human ubiquitin ligase HUWE1 has key roles in tumorigenesis, yet it is unkown how its activity is regulated. We present the crystal structure of a C-terminal part of HUWE1, including the catalytic domain, and reveal an asymmetric auto-inhibited dimer. We show that HUWE1 dimerizes in solution and self-associates in cells, and that both occurs through the crystallographic dimer interface. We demonstrate that HUWE1 is inhibited in cells and that it can be activated by disruption of the dimer interface. We identify a conserved segment in HUWE1 that counteracts dimer formation by associating with the dimerization region intramolecularly. Our studies reveal, intriguingly, that the tumor suppressor p14ARF binds to this segment and may thus shift the conformational equilibrium of HUWE1 toward the inactive state. We propose a model, in which the activity of HUWE1 underlies conformational control in response to physiological cues-a mechanism that may be exploited for cancer therapy.
authors.affiliation: Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.
authors.forename: Bodo
authors.initials: B
authors.lastname: Sander
authors.affiliation: Comprehensive Cancer Center Mainfranken, Würzburg, Germany.|Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Wenshan
authors.initials: W
authors.lastname: Xu
authors.affiliation: Comprehensive Cancer Center Mainfranken, Würzburg, Germany.|Theodor-Boveri-Institute, Biocenter, University of Würzburg, Würzburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Eilers
authors.affiliation: Comprehensive Cancer Center Mainfranken, Würzburg, Germany.|Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany.
authors.forename: Nikita
authors.initials: N
authors.lastname: Popov
authors.affiliation: Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.
authors.forename: Sonja
authors.identifier: 0000-0002-9639-2381
authors.initials: S
authors.lastname: Lorenz
mesh_terms: D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D025803:Tumor Suppressor Protein p14ARF; D025521:Tumor Suppressor Proteins; C502830:HUWE1 protein, human; D044767:Ubiquitin-Protein Ligases
keywords: HECT ligase; HUWE1; X-ray crystallography; biophysics; enzyme regulation; human; p14ARF; structural biology; ubiquitin