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

Mol Biol Cell. 2006 Mar;17(3):1164-75. doi: 10.1091/mbc.e05-11-1039. Epub 2005 Dec 28.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport
  • Ceramides / biosynthesis
  • Eukaryotic Initiation Factor-2B / metabolism
  • Gene Deletion
  • Gene Expression
  • Heat-Shock Proteins / genetics
  • Heat-Shock Response / genetics*
  • Peptide Chain Initiation, Translational*
  • Peptide Initiation Factors / metabolism
  • Phosphorylation
  • Protein Kinases / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Signal Transduction
  • Sphingolipids / biosynthesis
  • Sphingolipids / metabolism*
  • Suppression, Genetic
  • Ubiquitin / metabolism

Substances

  • Ceramides
  • Eukaryotic Initiation Factor-2B
  • Heat-Shock Proteins
  • Peptide Initiation Factors
  • RNA, Messenger
  • Saccharomyces cerevisiae Proteins
  • Sphingolipids
  • Ubiquitin
  • eIF4E-associated protein Eap1
  • HsP104 protein, S cerevisiae
  • Protein Kinases