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Spontaneous Calcium-Independent Dimerization of the Isolated First Domain of Neural Cadherin.
Davila, Samantha; Liu, Peilu; Smith, Alexis; Marshall, Alan G; Pedigo, Susan.
Afiliação
  • Davila S; Department of Chemistry and Biochemistry , University of Mississippi , University , Mississippi 38677 , United States.
  • Liu P; Department of Chemistry & Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States.
  • Smith A; Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States.
  • Marshall AG; Department of Chemistry and Biochemistry , University of Mississippi , University , Mississippi 38677 , United States.
  • Pedigo S; Department of Chemistry & Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States.
Biochemistry ; 57(45): 6404-6415, 2018 11 13.
Article em En | MEDLINE | ID: mdl-30387993
ABSTRACT
Cadherins are calcium-dependent, transmembrane adhesion molecules that assemble through direct noncovalent association of their N-terminal extracellular modular domains. As the transmembrane component of adherens junctions, they indirectly link adherent cells' actin cytoskeletons. Here, we investigate the most distal extracellular domain of neural cadherin (N-cadherin), a protein required at excitatory synapses, the site of long-term potentiation. This domain is the site of the adhesive interface, and it forms a dimer spontaneously without binding calcium, a surprising finding given that calcium binding is required for proper physiological function. A critical tryptophan at position 2, W2, provides a spectroscopic probe for the "closed" monomer and strand-swapped dimer. Spectroscopic studies show that W2 remains docked in the two forms but has a different apparent interaction with the hydrophobic pocket. Size-exclusion chromatography was used to measure the levels of the monomer and dimer over time to study the kinetics and equilibria of the unexpected spontaneous dimer formation ( Kd = 130 µM; τ = 2 days at 4 °C). Our results support the idea that NCAD1 is missing critical contacts that facilitate the rapid exchange of the ßA-strand. Furthermore, the monomer and dimer have equivalent and exceptionally high intrinsic stability for a 99-residue Ig-like domain with no internal disulfides ( Tm = 77 °C; Δ H = 85 kcal/mol). Ultimately, a complete analysis of synapse dynamics requires characterization of the kinetics and equilibria of N-cadherin. The studies reported here take a reductionist approach to understanding the essential biophysics of an atypical Ig-like domain that is the site of the adhesive interface of N-cadherin.
Assuntos

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Conformação Proteica / Caderinas / Multimerização Proteica Tipo de estudo: Prognostic_studies Limite: Humans Idioma: En Revista: Biochemistry Ano de publicação: 2018 Tipo de documento: Article País de afiliação: Estados Unidos

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Conformação Proteica / Caderinas / Multimerização Proteica Tipo de estudo: Prognostic_studies Limite: Humans Idioma: En Revista: Biochemistry Ano de publicação: 2018 Tipo de documento: Article País de afiliação: Estados Unidos