title: Regulation of Protein Interactions byMpsOneBinder (MOB1) Phosphorylation.
abstract: MOB1 is a multifunctional protein best characterized for its integrative role in regulating Hippo and NDR pathway signaling in metazoans and the Mitotic Exit Network in yeast. Human MOB1 binds both the upstream kinases MST1 and MST2 and the downstream AGC group kinases LATS1, LATS2, NDR1, and NDR2. Binding of MOB1 to MST1 and MST2 is mediated by its phosphopeptide-binding infrastructure, the specificity of which matches the phosphorylation consensus of MST1 and MST2. On the other hand, binding of MOB1 to the LATS and NDR kinases is mediated by a distinct interaction surface on MOB1. By assembling both upstream and downstream kinases into a single complex, MOB1 facilitates the activation of the latter by the former through a trans-phosphorylation event. Binding of MOB1 to its upstream partners also renders MOB1 a substrate, which serves to differentially regulate its two protein interaction activities (at leastin vitro). Our previous interaction proteomics analysis revealed that beyond associating with MST1 (and MST2), MOB1A and MOB1B can associate in a phosphorylation-dependent manner with at least two other signaling complexes, one containing the Rho guanine exchange factors (DOCK6-8) and the other containing the serine/threonine phosphatase PP6. Whether these complexes are recruited through the same mode of interaction as MST1 and MST2 remains unknown. Here, through a comprehensive set of biochemical, biophysical, mutational and structural studies, we quantitatively assess how phosphorylation of MOB1A regulates its interaction with both MST kinases and LATS/NDR family kinasesin vitroUsing interaction proteomics, we validate the significance of ourin vitrostudies and also discover that the phosphorylation-dependent recruitment of PP6 phosphatase and Rho guanine exchange factor protein complexes differ in key respects from that elucidated for MST1 and MST2. Together our studies confirm and extend previous work to delineate the intricate regulatory steps in key signaling pathways.
authors.affiliation: From the ‡Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada, M5G 1X5.|§Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.
authors.forename: Shawn
authors.initials: S
authors.lastname: Xiong
authors.affiliation: From the ‡Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada, M5G 1X5.
authors.forename: Amber L
authors.identifier: 0000-0003-0057-6686
authors.initials: AL
authors.lastname: Couzens
authors.affiliation: From the ‡Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada, M5G 1X5.
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Kean
authors.affiliation: From the ‡Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada, M5G 1X5.
authors.forename: Daniel Y
authors.initials: DY
authors.lastname: Mao
authors.affiliation: From the ‡Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada, M5G 1X5.|¶The Institute of Cancer Research, Divisions of Structural Biology and Cancer Biology, London, UK, SW7 3RP.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Guettler
authors.affiliation: ‖NE-CAT APS, Building 436E, Argonne National Lab, 9700 S. Cass Avenue, Argonne, Illinois 60439.
authors.forename: Igor
authors.initials: I
authors.lastname: Kurinov
authors.affiliation: From the ‡Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada, M5G 1X5; gingras@lunenfeld.ca sicheri@lunenfeld.ca.|**Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.
authors.forename: Anne-Claude
authors.identifier: 0000-0002-6090-4437
authors.initials: AC
authors.lastname: Gingras
authors.affiliation: From the ‡Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada, M5G 1X5; gingras@lunenfeld.ca sicheri@lunenfeld.ca.|§Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.|**Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.
authors.forename: Frank
authors.initials: F
authors.lastname: Sicheri
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics; D064067:Rho Guanine Nucleotide Exchange Factors / Q000378:metabolism; D000090742:Serine-Threonine Kinase 3; D000099317:Hippo Kinases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D047908:Intracellular Signaling Peptides and Proteins; D010749:Phosphoprotein Phosphatases; D017346:Protein Serine-Threonine Kinases; D064067:Rho Guanine Nucleotide Exchange Factors; D000090742:Serine-Threonine Kinase 3; C496255:MOB1B protein, human; C092745:LATS1 protein, human; C095566:STK4 protein, human; D000099317:Hippo Kinases; C097835:STK3 protein, human; C491614:STK38 protein, human; C572633:protein phosphatase-6 SAPSP1 subunit, human