Interdomain tilt angle determines integrin-dependent function of the ninth and tenth FIII domains of human fibronectin.
Integrins are an important family of signaling receptors that mediate diverse cellular processes. The binding of the abundant extracellular matrix ligand fibronectin to integrins alpha(5)beta(1) and alpha(v)beta(3) is known to depend upon the Arg-Gly-Asp (RGD) motif on the tenth fibronectin FIII domain. The adjacent ninth FIII domain provides a synergistic effect on RGD-mediated integrin alpha(5)beta(1) binding and downstream function. The precise molecular basis of this synergy remains elusive. Here we have dissected further the function of FIII9 in integrin binding by analyzing the biological activity of the FIII9-10 interdomain interface variants and by determining their structural and dynamic properties in solution. We demonstrate that the contribution of FIII9 to both alpha(5)beta(1) and alpha(v)beta(3) binding and downstream function critically depends upon the interdomain tilt between the FIII9 and FIII10 domains. Our data suggest that modulation of integrin binding by FIII9 may arise in part from its steric properties that determine accessibility of the RGD motif. These findings have wider implications for mechanisms of integrin-ligand binding in the physiological context.
Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom.
Harri
H
Altroff
Robin
R
Schlinkert
Christopher F
CF
van der Walle
Andrea
A
Bernini
Iain D
ID
Campbell
Jörn M
JM
Werner
Helen J
HJ
Mardon
D020816:Amino Acid Motifs; D002448:Cell Adhesion; D004247:DNA / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005353:Fibronectins / Q000737:chemistry*; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D016023:Integrins / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
D004220:Disulfides; D005353:Fibronectins; D039302:Integrin alphaVbeta3; D016023:Integrins; D008024:Ligands; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid; D004247:DNA