Sphingoid base is required for translation initiation during heat stress in Saccharomyces cerevisiae.

نویسندگان

  • Karsten D Meier
  • Olivier Deloche
  • Kentaro Kajiwara
  • Kouichi Funato
  • Howard Riezman
چکیده

Sphingolipids are required for many cellular functions including response to heat shock. We analyzed the yeast lcb1-100 mutant, which is conditionally impaired in the first step of sphingolipid biosynthesis and shows a strong decrease in heat shock protein synthesis and viability. Transcription and nuclear export of heat shock protein mRNAs is not affected. However, lcb1-100 cells exhibited a strong decrease in protein synthesis caused by a defect in translation initiation under heat stress conditions. The essential lipid is sphingoid base, not ceramide or sphingoid base phosphates. Deletion of the eIF4E-binding protein Eap1p in lcb-100 cells restored translation of heat shock proteins and increased viability. The translation defect during heat stress in lcb1-100 was due at least partially to a reduced function of the sphingoid base-activated PKH1/2 protein kinases. In addition, depletion of the translation initiation factor eIF4G was observed in lcb1-100 cells and ubiquitin overexpression allowed partial recovery of translation after heat stress. Taken together, we have shown a requirement for sphingoid bases during the recovery from heat shock and suggest that this reflects a direct lipid-dependent signal to the cap-dependent translation initiation apparatus.

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Sphingoid Base Is Required for Translation Initiation during Heat Stress in Saccharomyces cerevisiae□D

§Department of Biochemistry, University of Geneva, CH-1211 Geneva 4, Switzerland; *Department of Biochemistry, Biozentrum of the University of Basel, CH-4056 Basel, Switzerland; †Department of Microbiology and Molecular Medicine, CMU, University of Geneva, CH-1211 Geneva 4, Switzerland; and ‡Graduate School of Biosphere Science, Faculty of Applied Biological Science, Hiroshima University, Higas...

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عنوان ژورنال:
  • Molecular biology of the cell

دوره 17 3  شماره 

صفحات  -

تاریخ انتشار 2006