The yeast Hog1 protein is both functionally and structurally similar to the mammalian p38, belonging to the same family of MAP kinases and responding to extracellular changes in osmolarity. Since p38 mediates LPS effects in mammalian cells, we now tested the responsiveness of Hog1 upon exposure of the yeast S. cerevisiae to bacterial LPS. In the presence of E. coli LPS (100 ng/mL) and to an endotoxically active, hexaacylated, synthetic lipid A (compound 506; 100 ng/mL), Hog1 becomes phosphorylated with a maximum of phosphorylation between 3-6 hours, whereas a tetraacylated, inactive form of lipid A (compound 406) did not cause any modification in the phosphorylation state of Hog1. A triple labelling immunocytochemical study showed that phosphorylated Hog1 translocates into the nucleus after 90 min incubation and becomes sparsely located in the cytoplasm. The translocation of the phospho-Hog1 is preceded by an increased expression of the HOG1 gene and concomitant with the expression of the Hog1 target gene, GPD1. We also observed that cells unable to synthesise Hog1 do not resist to LPS as efficiently as wild-type cells. We conclude that the yeast S. cerevisiae is able to respond to the presence of gram-negative bacteria endotoxin, and that Hog1 is involved in this response.
|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||Reference||Annotation Extension|
|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||Conditions||Strain||Source||Reference|