Modulation of thermoprotection and translational thermotolerance induced by Semliki Forest virus capsid protein.
Low amounts of Semliki Forest virus capsid protein transferred into target cells by electroporation-mediated delivery (10(3)-10(4) molecules incorporated/cell) confer thermal resistance resulting in enhanced survival. Furthermore, when exposed to 43 degrees C, these cells display an enhanced expression of heat-shock protein-70 and a translational thermotolerance. Similarly, low amounts of capsid protein transferred into cells in which transcription is blocked by actinomycin D, also protect the translational machinery at 43 degrees C. In a cell-free translation system, added capsid protein appears to modulate translational efficiency of endogenous mRNAs. At approximately 1 molecule/ribosome, capsid protein is able to enhance translation at 30 degrees C and at 43 degrees C. In contrast, high concentrations of capsid protein are responsible for a marked inhibition of protein synthesis at 30 degrees C, but only hamper translational thermotolerance at 43 degrees C. Our results favor the hypothesis that small amounts of capsid protein trigger a chaperone-like activity that is able to protect the translational machinery from thermal damage.
Michel
M R
MR
Institute of Medical Microbiology, University of Berne, Switzerland.
Favre
D
D
Studer
E
E
Arrigo
A P
AP
Kempf
C
C
D000220:Adaptation, Biological; D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D018274:Electroporation; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D006358:Hot Temperature; D006801:Humans; D014176:Protein Biosynthesis / Q000187:drug effects / Q000502:physiology*; D012672:Semliki forest virus; D014759:Viral Envelope Proteins / Q000494:pharmacology*
D006360:Heat-Shock Proteins; D014759:Viral Envelope Proteins