title: Structural Basis for the Interaction of a Human Small Heat Shock Protein with the 14-3-3 Universal Signaling Regulator.
abstract: By interacting with hundreds of protein partners, 14-3-3 proteins coordinate vital cellular processes. Phosphorylation of the small heat shock protein, HSPB6, within its intrinsically disordered N-terminal domain activates its interaction with 14-3-3, ultimately triggering smooth muscle relaxation. After analyzing the binding of an HSPB6-derived phosphopeptide to 14-3-3 using isothermal calorimetry and X-ray crystallography, we have determined the crystal structure of the complete assembly consisting of the 14-3-3 dimer and full-length HSPB6 dimer and further characterized this complex in solution using fluorescence spectroscopy, small-angle X-ray scattering, and limited proteolysis. We show that selected intrinsically disordered regions of HSPB6 are transformed into well-defined conformations upon the interaction, whereby an unexpectedly asymmetric structure is formed. This structure provides the first atomic resolution snapshot of a human small HSP in functional state, explains how 14-3-3 proteins sequester their regulatory partners, and can inform the design of small-molecule interaction modifiers to be used as myorelaxants.
authors.affiliation: Laboratory of Structural Biochemistry of Proteins, A.N. Bach Institute of Biochemistry, Federal Research Center "Fundamentals of Biotechnology", Russian Academy of Sciences, 119071 Moscow, Russia. Electronic address: nikolai.sluchanko@mail.ru.
authors.forename: Nikolai N
authors.initials: NN
authors.lastname: Sluchanko
authors.affiliation: Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Beelen
authors.affiliation: Laboratory of Protein Conformational Polymorphism in Health and Disease, Engelhardt Institute of Molecular Biology, 119991 Moscow, Russia.
authors.forename: Alexandra A
authors.initials: AA
authors.lastname: Kulikova
authors.affiliation: Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Weeks
authors.affiliation: York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, UK.
authors.forename: Alfred A
authors.initials: AA
authors.lastname: Antson
authors.affiliation: Department of Biochemistry, School of Biology, Moscow State University, 119991 Moscow, Russia.
authors.forename: Nikolai B
authors.initials: NB
authors.lastname: Gusev
authors.affiliation: Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium. Electronic address: sergei.strelkov@kuleuven.be.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Strelkov
mesh_terms: D048948:14-3-3 Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020816:Amino Acid Motifs; D001665:Binding Sites; D014408:Biomarkers, Tumor / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005095:Exoribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D050886:HSP20 Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D064267:Intrinsically Disordered Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013379:Substrate Specificity
chemical_list: D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor; D050886:HSP20 Heat-Shock Proteins; C494382:HSPB6 protein, human; D064267:Intrinsically Disordered Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; D005095:Exoribonucleases; C413442:SFN protein, human
keywords: 14-3-3 proteins; conformational change; crystal structure; intrinsically disordered regions; phosphopeptides; protein-protein interaction; regulatory complex; small heat shock proteins; small-angle X-ray scattering; smooth muscle relaxation