Homophilic adhesion of E-cadherin occurs by a co-operative two-step interaction of N-terminal domains.
Cluster formation of E-cadherin on the cell surface is believed to be of major importance for cell-cell adhesion. To mimic this process the extracellular part of mouse E-cadherin (ECAD) was recombinantly fused to the assembly domain of rat cartilage oligomeric matrix protein (COMP), resulting in the chimeric protein ECAD-COMP. The COMP domain formed a five-stranded alpha-helical coiled-coil. This enabled the formation of a pentameric ECAD with bundled C-termini and free N-termini. The pentameric protein construct ECAD-COMP and the monomeric ECAD were expressed in human embryonal kidney 293 cells. Electron microscopy, analytical ultracentrifugation, solid phase binding and cell attachment assays revealed that pentamers showed strong self-association and cell attachment, whereas monomers exhibited no activity. At the high internal concentration in the pentamer the N-terminal EC1 domains of two E-cadherin arms interact to form a ring-like structure. Then the paired domains interact with a corresponding pair from another pentamer. None of the four other extracellular domains of E-cadherin is involved in this interaction. Based on these results, an in vivo mechanism is proposed whereby two N-terminal domains of neighbouring E-cadherins at the cell surface first form a pair, which binds with high affinity to a similar complex on another cell. The strong dependence of homophilic interactions on C-terminal clustering points towards a regulation of E-cadherin mediated cell-cell adhesion via lateral association.
Tomschy
A
A
Abteilung für Biophysikalische Chemie, Biozentrum, Universität Basel, Switzerland.
Fauser
C
C
Landwehr
R
R
Engel
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015820:Cadherins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D064236:Cartilage Oligomeric Matrix Protein; D002448:Cell Adhesion; D002460:Cell Line; D017931:DNA Primers; D016326:Extracellular Matrix Proteins; D015870:Gene Expression; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D064235:Matrilin Proteins; D051379:Mice; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D014407:Tumor Cells, Cultured
D015820:Cadherins; D064236:Cartilage Oligomeric Matrix Protein; C000611838:Cdh1 protein, mouse; D017931:DNA Primers; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C577540:Matn1 protein, mouse; D064235:Matrilin Proteins; D011993:Recombinant Fusion Proteins; C577553:TSP5 protein, human