Effect of heat shock on ribosome structure: appearance of a new ribosome-associated protein.

Abstract

After a nonlethal but heat shock protein-inducing hyperthermic treatment, ribosomes isolated from Tetrahymena thermophila contained an additional 22-kilodalton protein (p22). When maximally ribosome associated, this protein was found to be on the small subunit in a 1:1 stoichiometric ratio with other ribosomal proteins. Using an antiserum directed against the purified 22-kilodalton protein, we found that non-heat-shocked and heat-shocked cells contain identical amounts of this protein, the only difference being that in the stressed cells p22 is entirely ribosome bound, whereas in the unstressed cells p22 has little or no detectable ribosome association. Because the two-dimensional electrophoretic properties of p22 showed no alterations after heat shock, this change in state of ribosome-p22 interaction does not appear to be caused by a chemical modification of p22. When not strongly ribosome associated, p22 is not found free in the cytoplasm. During that time in heat shock when p22 is first becoming ribosome associated, it is found preferentially on polysomal ribosomes. Subsequently, all ribosomes, whether polysome bound or not, obtain a bound p22. The functional significance of this association is discussed.

A highly evolutionarily conserved mitochondrial protein is structurally related to the protein encoded by the Escherichia coli groEL gene.

“…Several of these proteins have been shown to exhibit a relatively high degree of evolutionary conservation in their DNA and amino acid sequences (2-5, 12, 24-26, 28), as well as in their subcellular compartmentalization (1,30,45,47). This conservation of structure and localization within the cell strongly suggests that these proteins perform similar functions in the different species in which these proteins are found.In Tetrahymena thermophila, shifting cells to 37 through 41°C induces the selective synthesis of a specific array of HSPs (16,18,19,33,49). Recently, we purified and characterized a minor member of this set of proteins.…”

“…In Tetrahymena thermophila, shifting cells to 37 through 41°C induces the selective synthesis of a specific array of HSPs (16,18,19,33,49). Recently, we purified and characterized a minor member of this set of proteins.…”

Biography of Arthur L. Horwich

“…Unbelievable!''' The gene involved in this foldingdefective behavior, called Hsp60, turned out to encode a heat-inducible subunit of a large double ring assembly found inside mitochondria a year before by Richard Hallberg (10). It now became increasingly clear that this protein was required under all conditions and that it mediated protein folding.…”

Evaluation of the Efficacy of the Stress Protein Response as a Biochemical Water Quality Biomonitoring Method

“…Relative intensities of bands on the film were quantitated using a laser densitometer (Ultroscan 2202, LKB Instruments; McMullin and Hallberg, 1986). …”