Regulation of the Chaperone Function of Small Hsps

Small heat shock proteins (sHsps) are ubiquitous molecular chaperones that represent a first line of defense against proteotoxic stress and prevent the aggregation of unfolding proteins. The most striking feature of sHsps is their ability to form higher-order oligomers. Within the last decade, especially the dynamic ensembles with a broad distribution of different oligomers, the diversity of assembly types and the regulation of their activity were in the focus of research. Interestingly, the activity of sHsps directly correlates to these structural features as it is regulated by changes in the composition of the ensembles. In this chapter, we describe the mechanisms known so far which are responsible for the activation of chaperone function and their linkage to changes in the structure of sHsps.