title: Crystal structures of Drosophila N-cadherin ectodomain regions reveal a widely used class of Ca²+-free interdomain linkers.
abstract: Vertebrate classical cadherins mediate selective calcium-dependent cell adhesion by mechanisms now understood at the atomic level. However, structures and adhesion mechanisms of cadherins from invertebrates, which are highly divergent yet function in similar roles, remain unknown. Here we present crystal structures of three- and four-tandem extracellular cadherin (EC) domain segments from Drosophila N-cadherin (DN-cadherin), each including the predicted N-terminal EC1 domain (denoted EC1') of the mature protein. While the linker regions for the EC1'-EC2' and EC3'-EC4' pairs display binding of three Ca(2+) ions similar to that of vertebrate cadherins, domains EC2' and EC3' are joined in a "kinked" orientation by a previously uncharacterized Ca(2+)-free linker. Biophysical analysis demonstrates that a construct containing the predicted N-terminal nine EC domains of DN-cadherin forms homodimers with affinity similar to vertebrate classical cadherins, whereas deleting the ninth EC domain ablates dimerization. These results suggest that, unlike their vertebrate counterparts, invertebrate cadherins may utilize multiple EC domains to form intercellular adhesive bonds. Sequence analysis reveals that similar Ca(2+)-free linkers are widely distributed in the ectodomains of both vertebrate and invertebrate cadherins.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
authors.forename: Xiangshu
authors.initials: X
authors.lastname: Jin
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Walker
authors.forename: Klára
authors.initials: K
authors.lastname: Felsövályi
authors.forename: Jeremie
authors.initials: J
authors.lastname: Vendome
authors.forename: Fabiana
authors.initials: F
authors.lastname: Bahna
authors.forename: Seetha
authors.initials: S
authors.lastname: Mannepalli
authors.forename: Filip
authors.initials: F
authors.lastname: Cosmanescu
authors.forename: Goran
authors.initials: G
authors.lastname: Ahlsen
authors.forename: Barry
authors.initials: B
authors.lastname: Honig
authors.forename: Lawrence
authors.initials: L
authors.lastname: Shapiro
mesh_terms: D000268:Adhesiveness; D000595:Amino Acid Sequence; D000818:Animals; D015820:Cadherins / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D018360:Crystallography, X-Ray; D029721:Drosophila Proteins / Q000737:chemistry* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
chemical_list: C570800:CadN protein, Drosophila; D015820:Cadherins; D029721:Drosophila Proteins; D002118:Calcium