Date of Award
Doctor of Philosophy
Genetics, Development and Cell Biology
Richard L. Hallberg
When T. thermophila is subjected to hyperthermal stress, it immediately but transiently represses the synthesis of the normal array of proteins (non-hsps) and induces the synthesis of the heat shock protein (hsps). These changes in protein synthetic patterns are controlled at both the transcriptional and translational levels;To determine whether the translational regulatory events could be correlated with changes in the protein synthetic machinery, heat shock induced modifications of the ribosomal proteins were investigated. Of particular interest was the heat shock induced association of a 22 kDa protein, p22, with the small subunit of the ribosome. The synthesis of p22 was not induced by heat shock but instead occurred during normal growth at 30°C where it was maintained in an apparent non-ribosome bound state at a concentration stoichiometric to the other ribosomal proteins. The kinetics of the association of p22 with the ribosome during heat shock correlated with the translationally regulated decline of hsp synthesis and return of non-hsp synthesis;The proteins synthesized by T. thermophila during heat shock include a 58 kDa protein, hsp58, which forms unusual oligomeric complexes. By in situ immunological localization and cell fractionation, hsp58 was found to be localized almost completely within mitochondria. Although present in non-heat shocked cells, the level of hsp58 in the cell as well as in the mitochondrial fraction increased 2-3-fold during heat shock;By immunological crossreactivity, hsp58 was found to be structurally homologous to a mitochondrial protein in Saccharomyces cerevisiae, Xenopus laevis, Zea mayes, and human lung cells. Additionally, a 59 kDa protein from Escherichia coli exhibited structural homology with hsp58. The cross-reacting protein from S. cerevisiae and E. coli exhibited heat inducibility and oligomeric complex formation. Based upon the unusual characteristics of the 59 kDa E. coli protein, we conclude this homologue of hsp58 is the protein product of the bacterial groE gene.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Thomas William McMullin
McMullin, Thomas William, "The metabolism and localization of two proteins during heat shock of Tetrahymena thermophila " (1987). Retrospective Theses and Dissertations. 9279.