Quaternary Structure of Chaperones from the Hsp70 System Determined by Small Angle X-Ray Scattering (SAXS) and Analytical Ultracentrifugation

High-resolution techniques, such as X-ray crystallography and nuclear magnetic resonance, are not always capable of providing insight into the quaternary structure of full-length forms of eukaryotic chaperones. This has somewhat limited the field’s ability to understand the mechanisms by which chaperones regulate and specify their functions. To fill this information gap, small angle X-ray scattering (SAXS) has been used to gain insight into the quaternary structure of chaperones and co-chaperones in the absence and in the presence of their ligands. This chapter will review selected structural biology publications of the Hsp70 system, in which SAXS was used to investigate the quaternary structure of these molecular chaperones, and will examine how analytical ultracentrifugation can be used as an important tool to validate SAXS data.

Keywords: Protein folding, Molecular chaperone, Heat shock protein, SAXS, Analytical ultracentrifugation, Hsp70, Hsp40, Nucleotide exchange factor.