Genetic and physical interaction of Ssp1 CaMKK and Rad24 14-3-3 during low pH and osmotic stress in fission yeast.
The Ssp1 calmodulin kinase kinase (CaMKK) is necessary for stress-induced re-organization of the actin cytoskeleton and initiation of growth at the new cell end following division in Schizosaccharomyces pombe. In addition, it regulates AMP-activated kinase and functions in low glucose tolerance. ssp1(-) cells undergo mitotic delay at elevated temperatures and G2 arrest in the presence of additional stressors. Following hyperosmotic stress, Ssp1-GFP forms transient foci which accumulate at the cell membrane and form a band around the cell circumference, but not co-localizing with actin patches. Hyperosmolarity-induced localization to the cell membrane occurs concomitantly with a reduction of its interaction with the 14-3-3 protein Rad24, but not Rad25 which remains bound to Ssp1. The loss of rad24 in ssp1(-) cells reduces the severity of hyperosmotic stress response and relieves mitotic delay. Conversely, overexpression of rad24 exacerbates stress response and concomitant cell elongation. rad24(-) does not impair stress-induced localization of Ssp1 to the cell membrane, however this response is almost completely absent in cells overexpressing rad24.
Department of Biology, Queen's University, 116 Barrie Street, Kingston, Ontario, Canada K7L 3N6.
Silja I
SI
Freitag
Jimson
J
Wong
Paul G
PG
Young
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D005838:Genotype; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D009997:Osmotic Pressure; D010641:Phenotype; D010766:Phosphorylation / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D011485:Protein Binding; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
D018797:Cell Cycle Proteins; D018840:HSP70 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; C111935:PSS1 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; C501114:rad24 protein, S pombe; C489574:rad25 protein, S pombe; D011189:Potassium Chloride; D004265:DNA Helicases
14-3-3; Rad24; Ssp1; hyperosmotic stress; pH; relocalization