Protein Folding and Chaperones

Abstract

Proteins fold via specific pathways to achieve their native structure. Protein structures are, however, inherently unstable, hence folding and unfolding are in equilibrium. Protein instability is a major concern inside the cell. Specialised proteins called molecular chaperones are, therefore, required to assist proteins in folding and to prevent aggregation of folding intermediates. Many different classes of chaperones are conserved throughout all kingdoms of life, many of which are known as heat shock proteins. Chaperones typically recognise hydrophobic patches, but the exact functions and mechanisms of action of the various chaperone classes are very different. The main chaperone classes Hsp70, Hsp90, Hsp100 and chaperonins all depend on ATPase cycles, whose activities are fine-tuned by co-chaperones. The molecular understanding of the mechanism of both chaperones and protein folding are key problems in present-day life sciences and molecular medicine.

Key Concepts

• Proteins fold via pathways.
• Protein structures are labile.
• Protein folding in vivo is assisted by molecular chaperones.
• Assisted protein folding requires ATP energy.
• Molecular chaperones are evolutionary conserved.
• Chaperone activity is controlled by co-chaperones and co-factors.
• Chaperone families differ in structure and function.