title: The preferential heterodimerization of human small heat shock proteins HSPB1 and HSPB6 is dictated by the N-terminal domain.
abstract: Small heat shock proteins are ATP-independent molecular chaperones. Their function is to bind partially unfolded proteins under stress conditions. In vivo, members of this chaperone family are known to preferentially assemble together forming large, polydisperse heterooligomers. The exact molecular mechanisms that drive specific heteroassociation are currently unknown. Here we study the oligomers formed between human HSPB1 and HSPB6. Using small-angle X-ray scattering we could characterize two distinct heterooligomeric species present in solution. By employing native mass spectrometry we show that such assemblies are formed purely from heterodimeric building blocks, in line with earlier cross-linking studies. Crucially, a detailed analysis of truncation variants reveals that the preferential association between these two sHSPs is solely mediated by their disordered N-terminal domains.
authors.affiliation: Laboratory for Biocrystallography, Dept. of Pharmaceutical and Pharmacological Sciences, KU Leuven, Belgium.
authors.forename: Michelle
authors.initials: M
authors.lastname: Heirbaut
authors.affiliation: Biomolecular and Analytical Mass Spectrometry Group, Dept. of Chemistry, University of Antwerp, Belgium; Centre for Proteomics, University of Antwerp, Belgium.
authors.forename: Frederik
authors.initials: F
authors.lastname: Lermyte
authors.affiliation: Biomolecular and Analytical Mass Spectrometry Group, Dept. of Chemistry, University of Antwerp, Belgium.
authors.forename: Esther M
authors.initials: EM
authors.lastname: Martin
authors.affiliation: Laboratory for Biocrystallography, Dept. of Pharmaceutical and Pharmacological Sciences, KU Leuven, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Beelen
authors.affiliation: Biomolecular and Analytical Mass Spectrometry Group, Dept. of Chemistry, University of Antwerp, Belgium.
authors.forename: Tim
authors.initials: T
authors.lastname: Verschueren
authors.affiliation: Biomolecular and Analytical Mass Spectrometry Group, Dept. of Chemistry, University of Antwerp, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: Sobott
authors.affiliation: Laboratory for Biocrystallography, Dept. of Pharmaceutical and Pharmacological Sciences, KU Leuven, Belgium. Electronic address: sergei.strelkov@kuleuven.be.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Strelkov
authors.affiliation: Laboratory for Biocrystallography, Dept. of Pharmaceutical and Pharmacological Sciences, KU Leuven, Belgium. Electronic address: stephen.weeks@kuleuven.be.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Weeks
mesh_terms: D050886:HSP20 Heat-Shock Proteins / Q000737:chemistry*; D055551:HSP27 Heat-Shock Proteins / Q000737:chemistry*; D006360:Heat-Shock Proteins; D006801:Humans; D013058:Mass Spectrometry; D018832:Molecular Chaperones / Q000737:chemistry; D008970:Molecular Weight; D016296:Mutagenesis; D000072417:Protein Domains; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000737:chemistry; D012542:Scattering, Radiation; D013696:Temperature
chemical_list: D050886:HSP20 Heat-Shock Proteins; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; C494382:HSPB6 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D011994:Recombinant Proteins
keywords: Chaperone; HSP20; HSP27; Heterooligomers; Native mass spectrometry; Small-angle x-ray scattering