Ribosomes as sensors of heat and cold shock in Escherichia coli.
Nearly all cells respond to an increase in temperature by inducing a set of proteins, called heat shock proteins (HSPs). Because a large number of other stress conditions induce the HSPs (or at least the most abundant ones), this response is often termed the universal stress response. However, a careful study of conditions that truly mimic a temperature shift suggested that these proteins are induced in response to a change in the translational capacity of the cell. To test this directly, Escherichia coli cells were treated with antibiotics that target the prokaryotic ribosome. Two-dimensional gels were used to evaluate the ability of these drugs to alter the rate of synthesis of the HSPs. One group of antibiotics induced the HSPs, whereas a second group repressed the HSPs and induced another set of proteins normally induced in response to a cold shock. Depending on the concentration used, the induction of the heat or cold shock proteins mimicked a mild or severe temperature shift. In addition, antibiotics of the cold shock-inducing group were found to block high temperature induction of the HSPs. The results implicate the ribosome as a prokaryotic sensor for the heat and cold shock response networks, a role it may serve in eukaryotes as well.
VanBogelen
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Department of Microbiology and Immunology, University of Michigan, Ann Arbor 48109-0620.
Neidhardt
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D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003080:Cold Temperature; D015180:Electrophoresis, Gel, Two-Dimensional; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D006358:Hot Temperature; D008954:Models, Biological; D012270:Ribosomes / Q000378:metabolism*; D013752:Tetracycline / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D006360:Heat-Shock Proteins; D013752:Tetracycline