Distinct Docking Mechanisms Mediate Interactions between the Msg5 Phosphatase and Mating or Cell Integrity Mitogen-activated Protein Kinases (MAPKs) in Saccharomyces cerevisiae

• Published in: The Journal of biological chemistry Vol. 286; no. 49; pp. 42037 - 42050
• Main Authors: Palacios, Lorena, Dickinson, Robin J., Sacristán-Reviriego, Almudena, Didmon, Mark P., Marín, María José, Martín, Humberto, Keyse, Stephen M., Molina, María
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 09-12-2011; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Motifs; Binding Motif; Binding Sites; Cell Signaling; DNA - metabolism; Dual Specificity Phosphoprotein Phosphatase; MAP Kinase Signaling System; MAP Kinases (MAPKs); Mitogen-Activated Protein Kinases - metabolism; Mlp1; Mutagenesis, Site-Directed; Mutation; Nuclear Proteins - metabolism; Phosphorylation; Protein Binding; Protein Structure, Tertiary; Protein Tyrosine Phosphatases - chemistry; Protein Tyrosine Phosphatases - metabolism; Protein-Protein Interactions; RNA-Binding Proteins; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - metabolism; Signal Transduction; Slt2; Two-Hybrid System Techniques; Yeast; Slt2; MAP Kinases (MAPKs); Yeast; Mlp1; Cell Signaling; Dual Specificity Phosphoprotein Phosphatase; Binding Motif; Protein-Protein Interactions
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111.286948

MAPK phosphatases (MKPs) are negative regulators of signaling pathways with distinct MAPK substrate specificities. For example, the yeast dual specificity phosphatase Msg5 dephosphorylates the Fus3 and Slt2 MAPKs operating in the mating and cell wall integrity pathways, respectively. Like other MAPK-interacting proteins, most MKPs bind MAPKs through specific docking domains. These include D-motifs, which contain basic residues that interact with acidic residues in the common docking (CD) domain of MAPKs. Here we show that Msg5 interacts not only with Fus3, Kss1, and Slt2 but also with the pseudokinase Slt2 paralog Mlp1. Using yeast two-hybrid and in vitro interaction assays, we have identified distinct regions within the N-terminal domain of Msg5 that differentially bind either the MAPKs Fus3 and Kss1 or Slt2 and Mlp1. Whereas a canonical D-site within Msg5 mediates interaction with the CD domains of Fus3 and Kss1, a novel motif (102IYT104) within Msg5 is involved in binding to Slt2 and Mlp1. Furthermore, mutation of this site prevents the phosphorylation of Msg5 by Slt2. This motif is conserved in Sdp1, another MKP that dephosphorylates Slt2, as well as in Msg5 orthologs from other yeast species. A region spanning amino acids 274–373 within Slt2 and Mlp1 mediates binding to this Msg5 motif in a CD domain-independent manner. In contrast, Slt2 uses its CD domain to bind to its upstream activator Mkk1. This binding flexibility may allow MAPK pathways to exploit additional regulatory controls in order to provide fine modulation of both pathway activity and specificity.
Background: Dual specificity protein phosphatases (DSPs) bind MAPKs through specific interaction motifs.
Results: A novel motif (IYT) in Msg5 mediates a common docking domain-independent interaction with the yeast cell integrity kinase Slt2.
Conclusion: Distinct mechanisms allow Msg5 to differentially bind Slt2 and Mlp1 or mating/pseudohyphal MAPKs Fus3 and Kss1.
Significance: Elucidation of the mechanisms by which MAPKs interact with key regulators is vital to understanding cell signaling.