title: Structural requirements for biological activity of the ninth and tenth FIII domains of human fibronectin.
abstract: The ninth and tenth type III domains of fibronectin each contain specific cell binding sequences, RGD in FIII10 and PHSRN in FIII9, that act synergistically in mediating cell adhesion. We investigated the relationship between domain-domain orientation and synergistic adhesive activity of the FIII9 and FIII10 pair of domains. The interdomain interaction of the FIII9-10 pair was perturbed by introduction of short flexible linkers between the FIII9 and FIII10 domains. Incremental extensions of the interdomain link between FIII9 and FIII10 reduced the initial cell attachment, but had a much more pronounced effect on the downstream cell adhesion events of spreading and phosphorylation of focal adhesion kinase. The extent of disruption of cell adhesion depended upon the length of the interdomain linker. Nuclear magnetic resonance spectroscopy of the wild type and mutant FIII9-10 proteins demonstrated that the structure of the RGD-containing loop is unaffected by domain-domain interactions. We conclude that integrin-mediated cell adhesion to the central cell binding domain of fibronectin depends not only upon specific interaction sites, but also on the relative orientation of these sites. These data have implications for the molecular mechanisms by which integrin-ligand interactions are achieved.
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology, University of Oxford, The Women's Centre, John Radcliffe Hospital, Headington, Oxford OX3 9DU, United Kingdom.
authors.forename: R P
authors.initials: RP
authors.lastname: Grant
authors.forename: C
authors.initials: C
authors.lastname: Spitzfaden
authors.forename: H
authors.initials: H
authors.lastname: Altroff
authors.forename: I D
authors.initials: ID
authors.lastname: Campbell
authors.forename: H J
authors.initials: HJ
authors.lastname: Mardon
mesh_terms: D001665:Binding Sites; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism; D005353:Fibronectins / Q000737:chemistry* / Q000502:physiology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D009842:Oligopeptides; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D015815:Cell Adhesion Molecules; D005353:Fibronectins; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human