Article: article from journal or magazin.
Sequential mechanism of solubilization and refolding of stable protein aggregates by a bichaperone network.
Proceedings of the National Academy of Sciences of the United States of America
A major activity of molecular chaperones is to prevent aggregation and refold misfolded proteins. However, when allowed to form, protein aggregates are refolded poorly by most chaperones. We show here that the sequential action of two Escherichia coli chaperone systems, ClpB and DnaK-DnaJ-GrpE, can efficiently solubilize excess amounts of protein aggregates and refold them into active proteins. Measurements of aggregate turbidity, Congo red, and 4,4'-dianilino-1, 1'-binaphthyl-5,5'-disulfonic acid binding, and of the disaggregation/refolding kinetics by using a specific ClpB inhibitor, suggest a mechanism where (i) ClpB directly binds protein aggregates, ATP induces structural changes in ClpB, which (ii) increase hydrophobic exposure of the aggregates and (iii) allow DnaK-DnaJ-GrpE to bind and mediate dissociation and refolding of solubilized polypeptides into native proteins. This efficient mechanism, whereby chaperones can catalytically solubilize and refold a wide variety of large and stable protein aggregates, is a major addition to the molecular arsenal of the cell to cope with protein damage induced by stress or pathological states.
Bacterial Proteins/metabolism, Escherichia coli Proteins, HSP40 Heat-Shock Proteins, HSP70 Heat-Shock Proteins/metabolism, Heat-Shock Proteins/metabolism, Heating, Malate Dehydrogenase/metabolism, Molecular Chaperones/metabolism, Protein Denaturation, Protein Folding, Solubility, Substrate Specificity
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