Ssp2 Binding Activates the Smk1 Mitogen-Activated Protein Kinase.
Mol Cell Biol
; 37(10)2017 05 15.
Article
em En
| MEDLINE
| ID: mdl-28223369
Smk1 is a meiosis-specific mitogen-activated protein kinase (MAPK) in Saccharomyces cerevisiae that couples spore morphogenesis to the completion of chromosome segregation. Similar to other MAPKs, Smk1 is controlled by phosphorylation of a threonine (T) and a tyrosine (Y) in its activation loop. However, it is not activated by a dual-specificity MAPK kinase. Instead, T207 in Smk1's activation loop is phosphorylated by the cyclin-dependent kinase (CDK)-activating kinase (Cak1), and Y209 is autophosphorylated in an intramolecular reaction that requires the meiosis-specific protein Ssp2. In this study, we show that Smk1 is catalytically inert unless it is bound by Ssp2. While Ssp2 binding activates Smk1 by a mechanism that is independent of activation loop phosphorylation, binding also triggers autophosphorylation of Y209 in Smk1, which, along with Cak1-mediated phosphorylation of T207, further activates the kinase. Autophosphorylation of Smk1 on Y209 also appears to modify the specificity of the MAPK by suppressing Y kinase and enhancing S/T kinase activity. We also found that the phosphoconsensus motif preference of Ssp2/Smk1 is more extensive than that of other characterized MAPKs. This study therefore defines a novel mechanism of MAPK activation requiring binding of an activator and also shows that MAPKs can be diversified to recognize unique phosphorylation motifs.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Saccharomyces cerevisiae
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Tirosina
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Regulação Fúngica da Expressão Gênica
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Proteínas Quinases Ativadas por Mitógeno
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Proteínas de Saccharomyces cerevisiae
Idioma:
En
Revista:
Mol Cell Biol
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
Estados Unidos