title: Autophosphorylation of the Smk1 MAPK is spatially and temporally regulated by Ssp2 during meiotic development in yeast.
abstract: Smk1 is a meiosis-specific MAPK that controls spore wall morphogenesis in Saccharomyces cerevisiae. Although Smk1 is activated by phosphorylation of the threonine (T) and tyrosine (Y) in its activation loop, it is not phosphorylated by a dual-specificity MAPK kinase. Instead, the T is phosphorylated by the cyclin-dependent kinase (CDK)-activating kinase, Cak1. The Y is autophosphorylated in an intramolecular reaction that requires a meiosis-specific protein named Ssp2. The meiosis-specific CDK-like kinase, Ime2, was previously shown to positively regulate Smk1. Here we show that Ime2 activity is required to induce the translation of SSP2 mRNA at anaphase II. Ssp2 protein is then localized to the prospore membrane, the structure where spore wall assembly takes place. Next the carboxy-terminal portion of Ssp2 forms a complex with Smk1 and stimulates the autophosphorylation of its activation-loop Y residue. These findings link Ime2 to Smk1 activation through Ssp2 and define a developmentally regulated mechanism for activating MAPK at specific locations in the cell.
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107.
authors.forename: Chong Wai
authors.initials: CW
authors.lastname: Tio
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107.
authors.forename: Gregory
authors.initials: G
authors.lastname: Omerza
authors.affiliation: Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109.
authors.forename: Sham
authors.initials: S
authors.lastname: Sunder
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107 edward.winter@jefferson.edu.
authors.forename: Edward
authors.initials: E
authors.lastname: Winter
mesh_terms: D000705:Anaphase / Q000502:physiology; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D005800:Genes, Fungal; D056726:Genetic Association Studies; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism*; D008540:Meiosis; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009024:Morphogenesis; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D062211:Spatio-Temporal Analysis; D013172:Spores, Fungal; D000095043:Cyclin-Dependent Kinase-Activating Kinase
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C460039:SSP2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C064979:IME2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; C443670:Smk1 protein, S cerevisiae; D000095043:Cyclin-Dependent Kinase-Activating Kinase