title: The Ama1-directed anaphase-promoting complex regulates the Smk1 mitogen-activated protein kinase during meiosis in yeast.
abstract: Smk1 is a meiosis-specific MAPK homolog in Saccharomyces cerevisiae that regulates the postmeiotic program of spore formation. Similar to other MAPKs, it is activated via phosphorylation of the T-X-Y motif in its regulatory loop, but the signals controlling Smk1 activation have not been defined. Here we show that Ama1, a meiosis-specific activator of the anaphase-promoting complex/cyclosome (APC/C), promotes Smk1 activation during meiosis. A weakened allele of CDC28 suppresses the sporulation defect of an ama1 null strain and increases the activation state of Smk1. The function of Ama1 in regulating Smk1 is independent of the FEAR network, which promotes exit from mitosis and exit from meiosis I through the Cdc14 phosphatase. The data indicate that Cdc28 and Ama1 function in a pathway to trigger Smk1-dependent steps in spore morphogenesis. We propose that this novel mechanism for controlling MAPK activation plays a role in coupling the completion of meiosis II to gamete formation.
authors.affiliation: Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, USA.
authors.forename: Christine M
authors.initials: CM
authors.lastname: McDonald
authors.forename: Katrina F
authors.initials: KF
authors.lastname: Cooper
authors.forename: Edward
authors.initials: E
authors.lastname: Winter
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D017489:CDC28 Protein Kinase, S cerevisiae / Q000502:physiology; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D008540:Meiosis / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017027:Protein Tyrosine Phosphatases / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D013172:Spores, Fungal / Q000235:genetics / Q000254:growth & development; D043743:Ubiquitin-Protein Ligase Complexes / Q000502:physiology*
chemical_list: C577515:Ama1 protein, S cerevisiae; C074860:CDC14 protein, S cerevisiae; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D029701:Saccharomyces cerevisiae Proteins; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D017489:CDC28 Protein Kinase, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; C443670:Smk1 protein, S cerevisiae; D017027:Protein Tyrosine Phosphatases