Molecular for the dynamic strength of the integrin α 4β1/VCAM-1 interaction

Xiaohui Zhang, Susan E. Craig, Hishani Kirby, Martin J. Humphries, Vincent T. Moy

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Abstract

Intercellular adhesion mediated by integrin α4β 1 and vascular cell adhesion molecule-1 (VCAM-1) plays a crucial role in both the rolling and firm attachment of leukocytes onto the vascular endothelium. Essential to the α4β1/VCAM-1 interaction is its mechanical strength that allows the complex to resist the large shear forces imposed by the bloodstream. Herein we employed single-molecule dynamic force spectroscopy to investigate the dynamic strength of the α4β1/VCAM-1 complex. Our force measurements revealed that the dissociation of the α4β 1/VCAM-1 complex involves overcoming at least two activation potential barriers: a steep inner barrier and a more elevated outer barrier. The inner barrier grants the complex the tensile strength to withstand large pulling forces (>50 pN) and was attributed to the ionic interaction between the chelated Mg2+ ion at the N-terminal A-domain of the β1 subunit of α4β1 and the carboxyl group of Asp-40 of VCAM-1 through the use of site-directed mutations. In general, additional mutations within the C-D loop of domain 1 of VCAM-1 suppressed both inner and outer barriers of the α4β 1/VCAM-1 complex, while a mutation at Asp-143 of domain 2 of VCAM-1 resulted in the suppression of the outer barrier, but not the inner barrier. In contrast, the outer barrier of α4β1/VCAM-1 complex was stabilized by integrin activation. Together, these findings provide a molecular explanation for the functionally relevant kinetic properties of the α4β1/ VCAM-1 interaction.

Original languageEnglish
Pages (from-to)3470-3478
Number of pages9
JournalBiophysical Journal
Volume87
Issue number5
DOIs
StatePublished - Nov 1 2004

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Vascular Cell Adhesion Molecule-1
Molecular Dynamics Simulation
Integrins
Mutation
Organized Financing
Tensile Strength
Vascular Endothelium
Spectrum Analysis
Leukocytes
Ions

ASJC Scopus subject areas

  • Biophysics

Cite this

Molecular for the dynamic strength of the integrin α 4β1/VCAM-1 interaction. / Zhang, Xiaohui; Craig, Susan E.; Kirby, Hishani; Humphries, Martin J.; Moy, Vincent T.

In: Biophysical Journal, Vol. 87, No. 5, 01.11.2004, p. 3470-3478.

Research output: Contribution to journalArticle

Zhang, Xiaohui ; Craig, Susan E. ; Kirby, Hishani ; Humphries, Martin J. ; Moy, Vincent T. / Molecular for the dynamic strength of the integrin α 4β1/VCAM-1 interaction. In: Biophysical Journal. 2004 ; Vol. 87, No. 5. pp. 3470-3478.
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