In vitro and in vivo reconstitution of the cadherin-catenin-actin complex from Caenorhabditis elegans.
The ternary complex of cadherin, beta-catenin, and alpha-catenin regulates actin-dependent cell-cell adhesion. alpha-Catenin can bind beta-catenin and F-actin, but in mammals alpha-catenin either binds beta-catenin as a monomer or F-actin as a homodimer. It is not known if this conformational regulation of alpha-catenin is evolutionarily conserved. The Caenorhabditis elegans alpha-catenin homolog HMP-1 is essential for actin-dependent epidermal enclosure and embryo elongation. Here we show that HMP-1 is a monomer with a functional C-terminal F-actin binding domain. However, neither full-length HMP-1 nor a ternary complex of HMP-1-HMP-2(beta-catenin)-HMR-1(cadherin) bind F-actin in vitro, suggesting that HMP-1 is auto-inhibited. Truncation of either the F-actin or HMP-2 binding domain of HMP-1 disrupts C. elegans development, indicating that HMP-1 must be able to bind F-actin and HMP-2 to function in vivo. Our study defines evolutionarily conserved properties of alpha-catenin and suggests that multiple mechanisms regulate alpha-catenin binding to F-actin.
Kwiatkowski
Adam V
AV
Department of Biology, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA.
Maiden
Stephanie L
SL
Pokutta
Sabine
S
Choi
Hee-Jung
HJ
Benjamin
Jacqueline M
JM
Lynch
Allison M
AM
Nelson
W James
WJ
Weis
William I
WI
Hardin
Jeff
J
D000199:Actins / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015820:Cadherins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D055503:Protein Multimerization; D053838:Scattering, Small Angle; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D014961:X-Ray Diffraction; D051178:alpha Catenin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D015820:Cadherins; D029742:Caenorhabditis elegans Proteins; D003598:Cytoskeletal Proteins; C442473:HMP-2 protein, C elegans; D051178:alpha Catenin; D049452:Green Fluorescent Proteins