The Srk1 protein kinase is a target for the Sty1 stress-activated MAPK in fission yeast.
The fission yeast stress-activated Sty1/Spc1 MAPK pathway responds to a similar range of stresses as do the mammalian p38 and SAPK/JNK MAPK pathways. In addition, sty1(-) cells are sterile and exhibit a G(2) cell cycle delay, indicating additional roles of Sty1 in meiosis and cell cycle progression. To identify novel proteins involved in stress responses, a microarray analysis of the Schizosaccharomyces pombe genome was performed to find genes that are up-regulated following exposure to stress in a Sty1-dependent manner. One such gene identified, srk1(+) (Sty1-regulated kinase 1), encodes a putative serine/threonine kinase homologous to mammalian calmodulin kinases. At the C terminus of Srk1 is a putative MAPK binding motif similar to that in the p38 substrates, MAPK-activated protein kinases 2 and 3. Indeed, we find that Srk1 is present in a complex with the Sty1 MAPK and is directly phosphorylated by Sty1. Furthermore, upon stress, Srk1 translocates from the cytoplasm to the nucleus in a process that is dependent on the Sty1 MAPK. Finally, we show that Srk1 has a role in regulating meiosis in fission yeast; following nitrogen limitation, srk1(-) cells enter meiosis significantly faster than wild-type cells and overexpression of srk1(+) inhibits the nitrogen starvation-induced arrest in G(1).
Smith
Deborah A
DA
School of Biochemistry and Genetics, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, United Kingdom.
Toone
W Mark
WM
Chen
Dongrong
D
Bahler
Jurg
J
Jones
Nic
N
Morgan
Brian A
BA
Quinn
Janet
J
D021581:Active Transport, Cell Nucleus; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D005434:Flow Cytometry; D005656:Fungal Proteins; D016193:G1 Phase; D016195:G2 Phase; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D008540:Meiosis; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism* / Q000502:physiology*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism* / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D015854:Up-Regulation
D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D006861:Hydrogen Peroxide; C407464:RCK2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C499611:SRK1 protein, S pombe; D020928:Mitogen-Activated Protein Kinases; C095409:sty1 protein, S pombe; D020929:Mitogen-Activated Protein Kinase Kinases; C072068:wis1 protein, S pombe; D009584:Nitrogen