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Structure. 2017 Feb 7;25(2):305-316. doi: 10.1016/j.str.2016.12.005. Epub 2017 Jan 12.

Structural Basis for the Interaction of a Human Small Heat Shock Protein with the 14-3-3 Universal Signaling Regulator.

Author information

1
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.
2
Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium.
3
Laboratory of Protein Conformational Polymorphism in Health and Disease, Engelhardt Institute of Molecular Biology, 119991 Moscow, Russia.
4
York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, UK.
5
Department of Biochemistry, School of Biology, Moscow State University, 119991 Moscow, Russia.
6
Laboratory for Biocrystallography, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium. Electronic address: sergei.strelkov@kuleuven.be.

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.

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

PMID:
28089448
PMCID:
PMC5321513
DOI:
10.1016/j.str.2016.12.005
[Indexed for MEDLINE]
Free PMC Article

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