The preferential heterodimerization of human small heat shock proteins HSPB1 and HSPB6 is dictated by the N-terminal domain

Michelle Heirbaut; Frederik Lermyte; Esther M Martin; Steven Beelen; Tim Verschueren; Frank Sobott; Sergei V Strelkov; Stephen D Weeks

doi:10.1016/j.abb.2016.10.002

The preferential heterodimerization of human small heat shock proteins HSPB1 and HSPB6 is dictated by the N-terminal domain

Arch Biochem Biophys. 2016 Nov 15:610:41-50. doi: 10.1016/j.abb.2016.10.002. Epub 2016 Oct 4.

Authors

Michelle Heirbaut¹, Frederik Lermyte², Esther M Martin³, Steven Beelen¹, Tim Verschueren³, Frank Sobott³, Sergei V Strelkov⁴, Stephen D Weeks⁵

Affiliations

¹ Laboratory for Biocrystallography, Dept. of Pharmaceutical and Pharmacological Sciences, KU Leuven, Belgium.
² Biomolecular and Analytical Mass Spectrometry Group, Dept. of Chemistry, University of Antwerp, Belgium; Centre for Proteomics, University of Antwerp, Belgium.
³ Biomolecular and Analytical Mass Spectrometry Group, Dept. of Chemistry, University of Antwerp, Belgium.
⁴ Laboratory for Biocrystallography, Dept. of Pharmaceutical and Pharmacological Sciences, KU Leuven, Belgium. Electronic address: sergei.strelkov@kuleuven.be.
⁵ Laboratory for Biocrystallography, Dept. of Pharmaceutical and Pharmacological Sciences, KU Leuven, Belgium. Electronic address: stephen.weeks@kuleuven.be.

PMID: 27717639
DOI: 10.1016/j.abb.2016.10.002

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.

Keywords: Chaperone; HSP20; HSP27; Heterooligomers; Native mass spectrometry; Small-angle x-ray scattering.

MeSH terms

HSP20 Heat-Shock Proteins / chemistry*
HSP27 Heat-Shock Proteins / chemistry*
Heat-Shock Proteins
Humans
Mass Spectrometry
Molecular Chaperones / chemistry
Molecular Weight
Mutagenesis
Protein Domains
Protein Multimerization
Recombinant Proteins / chemistry
Scattering, Radiation
Temperature

Substances

HSP20 Heat-Shock Proteins
HSP27 Heat-Shock Proteins
HSPB1 protein, human
HSPB6 protein, human
Heat-Shock Proteins
Molecular Chaperones
Recombinant Proteins