The role of heat-shock proteins in thermotolerance
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The role of heat-shock proteins (hsps) in thermotolerance was examined in the budding yeast Saccharomyces cerevisiae and in the fruit fly Drosophila melanogaster. In yeast cells, the major protein responsible for thermotolerance is hsp 100. In cells carrying mutations in the hsp 100 gene, HSP 104, growth is normal at both high and low temperatures, but the ability of cells to survive extreme temperatures is severely impaired. The loss of thermotolerance is apparently due to the absence of the hsp 104 protein itself because, with the exception of the hsp 104 protein, no differences in protein profiles were observed between mutant and wild-type cells. Aggregates found in mutant cells at high temperatures suggest that the cause of death may be the accumulation of denatured proteins. No differences in the rates of protein degradation were observed between mutant and wild-type cells. This, and genetic analysis of cells carrying multiple hsp 70 and hsp 104 mutations, suggests that the primary function of hsp 104 is to rescue proteins from denaturation rather than to degrade them once they have been denatured. Drosophila cells do not produce a protein in the hsp 100 class in response to high temperatures. In this organism, hsp 70 appears to be the primary protein involved in thermotolerance. Thus, the relative importance of different hsps in thermotolerance changes from organism to organism.
KeywordsYeast Cell Mutant Cell Nurse Cell Yeast Protein Sodium Arsenite
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- Gottesman, S., Squires, C, Pichersky, E., Carrington, M., Hobbs, M., Mattick, J.S., Dalrymple, B., Kuramitsu, H., Shiroza, T. & Foster, T. 1990 Conservation of the regulatory subunit for the Clp ATP-dependent protease in prokaryotes and eukaryotes. Proc. natn. Acad. Sci. U.S.A. 87, 3513–3517.CrossRefGoogle Scholar
- Nover, L. 1991 Heat shock response, 1st edn. Boca Raton, Florida: CRC Press.Google Scholar
- Sanchez, Y., Parsell, D.A., Taulien, J., Vogel, Craig, E.A. & Lindquist, S.L. 1993 Genetic evidence for a functional relationship between hsp 104 and hsp 70. (In preparation.)Google Scholar
- Welte, M.A., Tetrault, J. & Lindquist, S. 1993 A new method for manipulating transgenes: improving thermotolerance in Drosophila embryos. (In preparation.)Google Scholar
- Werner, W.M., Stone, D.E. & Craig, E.A. 1987 Complex interactions among members of an essential subfamily of hsp 70 genes in Saccharomyces cerevisiae. Molec. Cell Biol. 7, 2568–2577.Google Scholar