ABSTRACT: BACKGROUND: Saccharomyces cerevisiae myosin type II-deficient myo1Delta strains remain viable and divide, despite the absence of a cytokinetic ring, by activation of the PKC1-dependent cell wall integrity pathway (CWIP). Since the myo1Delta transcriptional fingerprint is a subset of the CWIP fingerprint, the myo1Delta strain may provide a simplified paradigm for cell wall stress survival. RESULTS: To explore the post-transcriptional regulation of the myo1Delta stress response, 1,301 differentially regulated ribosome-bound mRNAs were identified by microarray analysis of which 204 were co-regulated by transcription and translation. Four categories of mRNA were significantly affected - protein biosynthesis, metabolism, carbohydrate metabolism, and unknown functions. Nine genes of the 20 CWIP fingerprint genes were post-transcriptionally regulated. Down and up regulation of selected ribosomal protein and cell wall biosynthesis mRNAs was validated by their distribution in polysomes from wild type and myo1Delta strains. Western blot analysis revealed accumulation of the phosphorylated form of eukaryotic translation initiation factor 2 (eIF2alpha-P) and a reduction in the steady state levels of the translation initiation factor eIF4Gp in myo1Delta strains. Deletion of GCN2 in myo1Delta abolished eIF2alphap phosphorylation, and showed a severe growth defect. The presence of P-bodies in myo1Delta strains suggests that the process of mRNA sequestration is active, however, the three representative down regulated RP mRNAs, RPS8A, RPL3 and RPL7B were present at equivalent levels in Dcp2p-mCh-positive immunoprecipitated fractions from myo1Delta and wild type cells. These same RP mRNAs were also selectively co-precipitated with eIF2alpha-P in myo1Delta strains. CONCLUSIONS: Quantitative analysis of ribosome-associated mRNAs and their polyribosome distributions suggests selective regulation of mRNA translation efficiency in myo1Delta strains. Inhibition of translation initiation factor eIF2alpha (eIF2alpha-P) in these strains was by Gcn2p-dependent phosphorylation. The increase in the levels of eIF2alpha-P; the genetic interaction between GCN2 and MYO1; and the reduced levels of eIF4Gp suggest that other signaling pathways, in addition to the CWIP, may be important for myo1Delta strain survival. Selective co-immunoprecipitation of RP mRNAs with eIF2alpha-P in myo1Delta strains suggests a novel mode of translational regulation. These results indicate that post-transcriptional control is important in the myo1Delta stress response and possibly other stresses in yeast.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|