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A hallmark of alpha-crystallin-type small heat shock proteins (sHsps) is their highly dynamic oligomeric structure which promotes intermolecular interactions involved in subunit exchange and substrate binding (chaperone-like activity). We studied the oligomeric features of two classes of bacterial sHsps by size exclusion chromatography and nanoelectrospray mass spectrometry. Proteins of both classes formed large complexes that rapidly dissociated upon dilution and at physiologically relevant heat shock temperatures. As the secondary structure was not perturbed, temperature- and concentration-dependent dissociations were fully reversible. Complexes formed between sHsps and the model substrate citrate synthase were stable and exceeded the size of sHsp oligomers. Small Hsps, mutated in a highly conserved glycine residue at the C-terminal end of the alpha-crystallin domain, formed labile complexes that disassembled more readily than the corresponding wild-type proteins. Reduced complex stability coincided with reduced chaperone activity.

Original publication

DOI

10.1111/j.1432-1033.2004.04180.x

Type

Journal article

Journal

Eur J Biochem

Publication Date

06/2004

Volume

271

Pages

2494 - 2503

Keywords

Chromatography, Circular Dichroism, Heat-Shock Proteins, Macromolecular Substances, Mass Spectrometry, Models, Molecular, Molecular Chaperones, Protein Structure, Quaternary, Protein Structure, Secondary, Protein Subunits, Rhizobium, Temperature