title: Phosphoregulation of the C. elegans cadherin-catenin complex.
abstract: Adherens junctions play key roles in mediating cell-cell contacts during tissue development. In Caenorhabditis elegans embryos, the cadherin-catenin complex (CCC), composed of the classical cadherin HMR-1 and members of three catenin families, HMP-1, HMP-2 and JAC-1, is necessary for normal blastomere adhesion, gastrulation, ventral enclosure of the epidermis and embryo elongation. Disruption of CCC assembly or function results in embryonic lethality. Previous work suggests that components of the CCC are subject to phosphorylation. However, the identity of phosphorylated residues in CCC components and their contributions to CCC stability and function in a living organism remain speculative. Using mass spectrometry, we systematically identify phosphorylated residues in the essential CCC subunits HMR-1, HMP-1 and HMP-2 in vivo. We demonstrate that HMR-1/cadherin phosphorylation occurs on three sites within its β-catenin binding domain that each contributes to CCC assembly on lipid bilayers. In contrast, phosphorylation of HMP-2/β-catenin inhibits its association with HMR-1/cadherin in vitro, suggesting a role in CCC disassembly. Although HMP-1/α-catenin is also phosphorylated in vivo, phosphomimetic mutations do not affect its ability to associate with other CCC components or interact with actin in vitro. Collectively, our findings support a model in which distinct phosphorylation events contribute to rapid CCC assembly and disassembly, both of which are essential for morphogenetic rearrangements during development.
authors.affiliation: Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706, U.S.A.
authors.forename: Sandhya
authors.initials: S
authors.lastname: Callaci
authors.affiliation: Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706, U.S.A.
authors.forename: Kylee
authors.initials: K
authors.lastname: Morrison
authors.affiliation: Department of Zoology and Program in Genetics, University of Wisconsin-Madison, Madison, WI 53706, U.S.A.
authors.forename: Xiangqiang
authors.initials: X
authors.lastname: Shao
authors.affiliation: Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706, U.S.A.
authors.forename: Amber L
authors.initials: AL
authors.lastname: Schuh
authors.affiliation: Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, U.S.A.
authors.forename: Yueju
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, U.S.A.
authors.forename: John R
authors.initials: JR
authors.lastname: Yates
authors.affiliation: Department of Zoology and Program in Genetics, University of Wisconsin-Madison, Madison, WI 53706, U.S.A.
authors.forename: Jeff
authors.initials: J
authors.lastname: Hardin
authors.affiliation: Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53706, U.S.A. audhya@wisc.edu.
authors.forename: Anjon
authors.initials: A
authors.lastname: Audhya
mesh_terms: D000818:Animals; D001757:Blastomeres / Q000378:metabolism*; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D051177:Catenins / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000196:embryology; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D051178:alpha Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D015820:Cadherins; D029742:Caenorhabditis elegans Proteins; D051177:Catenins; D003598:Cytoskeletal Proteins; C000600734:HMP-1 protein, C elegans; C442473:HMP-2 protein, C elegans; C000600735:JAC-1 protein, C elegans; D046912:Multiprotein Complexes; D051178:alpha Catenin; C450060:hmr-1 protein, C elegans
keywords: conformational change; recombinant protein expression; small-angle X-ray scattering (SAXS)