Robust heat shock induces eIF2alpha-phosphorylation-independent assembly of stress granules containing eIF3 and 40S ribosomal subunits in budding yeast, Saccharomyces cerevisiae.
Environmental stresses inducing translation arrest are accompanied by the deposition of translational components into stress granules (SGs) serving as mRNA triage sites. It has recently been reported that, in Saccharomyces cerevisiae, formation of SGs occurs as a result of a prolonged glucose starvation. However, these SGs did not contain eIF3, one of hallmarks of mammalian SGs. We have analyzed the effect of robust heat shock on distribution of eIF3a/Tif32p/Rpg1p and showed that it results in the formation of eIF3a accumulations containing other eIF3 subunits, known yeast SG components and small but not large ribosomal subunits and eIF2alpha/Sui2p. Interestingly, under these conditions, Dcp2p and Dhh1p P-body markers also colocalized with eIF3a. Microscopic analyses of the edc3Deltalsm4DeltaC mutant demonstrated that different scaffolding proteins are required to induce SGs upon robust heat shock as opposed to glucose deprivation. Even though eIF2alpha became phosphorylated under these stress conditions, the decrease in polysomes and formation of SGs occurred independently of phosphorylation of eIF2alpha. We conclude that under specific stress conditions, such as robust heat shock, yeast SGs do contain eIF3 and 40S ribosomes and utilize alternative routes for their assembly.
Grousl
Tomás
T
Laboratory of Cell Reproduction, Institute of Microbiology of the AS CR, v.v.i., Prague, Czech Republic.
Ivanov
Pavel
P
Frýdlová
Ivana
I
Vasicová
Pavla
P
Janda
Filip
F
Vojtová
Jana
J
Malínská
Katerina
K
Malcová
Ivana
I
Nováková
Lenka
L
Janosková
Dana
D
Valásek
Leos
L
Hasek
Jirí
J
D003513:Cycloheximide / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D015536:Down-Regulation / Q000502:physiology; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D039621:Eukaryotic Initiation Factor-3 / Q000378:metabolism*; D018869:Heat-Shock Response / Q000187:drug effects / Q000502:physiology*; D030781:Organisms, Genetically Modified; D010766:Phosphorylation / Q000502:physiology; D014176:Protein Biosynthesis / Q000187:drug effects / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D054682:Ribosome Subunits, Small, Eukaryotic / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology; D014018:Tissue Distribution
D015852:Eukaryotic Initiation Factor-2; D039621:Eukaryotic Initiation Factor-3; D011500:Protein Synthesis Inhibitors; D029701:Saccharomyces cerevisiae Proteins; D003513:Cycloheximide; C512912:GCN2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases