Báo cáo khoa học: Small heat shock protein Hsp27 prevents heat-induced aggregation of F-actin by forming soluble complexes with denatured actin

Small Heat Shock Protein Hsp27 Prevents Heat-Induced Aggregation of F-actin by Forming Soluble Complexes with Denatured Actin

Authors: Anastasia V. Pivovarova, Natalia A. Chebotareva, Ivan S. Chernik, Nikolai B. Gusev, and Dmitrii I. Levitsky

Field: Biochemistry, Cell Biology

Document Content: This research investigates the mechanism by which small heat shock protein Hsp27 (Hsp27) prevents the aggregation of F-actin when exposed to heat. Previous studies indicated that Hsp27 hinders the aggregation of thermally denatured F-actin by forming soluble complexes with it. This work applies dynamic light scattering (DLS), analytical ultracentrifugation, and size exclusion chromatography (SEC) to analyze these complexes. The study utilized a recombinant human Hsp27 mutant, Hsp27-3D, which mimics natural phosphorylation, to examine the properties of complexes formed with denatured actin. The findings demonstrate that these complexes form upon heating and coincide with F-actin denaturation. The size of the actin-Hsp27-3D complexes decreases as the concentration of Hsp27-3D increases, with saturation occurring at approximately equimolar concentrations of Hsp27-3D and actin. Under these conditions, the complexes exhibit a hydrodynamic radius of approximately 16 nm and a molecular mass of about 2 MDa. The proposed mechanism suggests that Hsp27-3D binds to denatured actin monomers or short oligomers, preventing their aggregation by forming small, highly soluble complexes. This process is crucial for protecting the cytoskeleton and the entire cell from damage caused by the accumulation of large, insoluble aggregates under heat shock conditions.

Detailed Table of Contents:

• Introduction
• Keywords
• Correspondence
• Abbreviations
• Results
• DLS studies of actin-Hsp27-3D complexes formed upon thermal denaturation of F-actin
• Analytical ultracentrifugation of the Hsp27-3D complexes with denatured actin
• Stoichiometry of the Hsp27-3D-actin complexes analyzed by SEC
• Discussion
• Experimental procedures
• Proteins
• F-actin aggregation
• DLS
• Analytical ultracentrifugation
• SEC
• Acknowledgements
• References