The small heat shock proteins of the nematode Caenorhabditis elegans: structure, regulation and biology.

Abstract

The first investigations of the heat shock response in C. elegans were carried out by analyzing the patterns of proteins synthesized by 35S-labeled nematodes cultured at various temperatures (Snutch and Baillie 1983). These experiments established a temperature profile for the heat shock response, identified the major molecular weight classes of heat shock proteins (Hsps) and noted the homology between Drosophila and C. elegans Hsp70 genes, based on crosshybridization experiments. In these studies, a prominent, labeled protein with an apparent molecular mass of 16 kDa was noted in heat shocked animals. Partial cDNAs encoding Hspl6 species were subsequently cloned, and these were the first small Hsp (sHsp) sequences determined after those of Drosophila, to which they were found to be related (Russnak et al. 1983). The Hsp 16 sequences of C. elegans thus provided the first indication that small Hsps of varying molecular masses from distantly related organisms were similar to each other and to the mammalian α-crystallins. The completion of the C. elegans genome sequence (The C. elegans Sequencing Consortium 1998) provides an opportunity to examine the entire complement of sHsps from this metazoan. This review will provide an overview of the structures, expression, developmental and tissue specificities and biochemical properties of the C. elegans sHsps which have been studied to date.