title: Interaction of ICAM-1 with beta 2-integrin CD11c/CD18: characterization of a peptide ligand that mimics a putative binding site on domain D4 of ICAM-1.
abstract: The integrin CD11c/CD18 plays a role in leukocyte and cell matrix adhesion and is highly expressed in certain hematopoietic malignancies. To better characterize ligand binding properties, we panned random peptide phage-display libraries over purified CD11c/CD18. We identified a phage expressing the circular peptide C-GRWSGWPADL-C. C-GRWSGWPADL-C phage bound specifically to CD11c/CD18 expressing monocytes but not CD11c/CD18 negative lymphocytes and showed 5 x 10(3)-fold higher binding to purified CD11c/CD18 than control phage, without binding to CD11b/CD18. Peptide sequence analysis revealed a similar sequence in domain D5 of ICAM-1 and an alternative, phase-shifted motif in domain D4. Surface plasmon resonance experiments demonstrated direct interaction of ICAM-1 and CD11c/CD18. A soluble fusion protein containing the extracellular domain of ICAM-1 abolished C-GRWSGWPADL-C phage binding to CD11c/CD18. Moreover, synthetic monomeric circular peptide C-GRWSGWPADL-C bound specifically to CD11c/CD18 and inhibited ICAM-1 binding. Its rather low binding affinity and inability to displace pentavalent C-GRWSGWPADL-C phage from CD11c/CD18 suggests that a multimeric display of the selected peptide is essential for high affinity binding. Using ICAM-1 deletion constructs, we showed that domain D4 is required for interaction with CD11c/CD18, suggesting that C-GRWSGWPADL-C phage binds specifically to CD11c/CD18 by structurally mimicking the interaction site on D4 of ICAM-1.
authors.affiliation: Department of Nephrology and Hypertension, Department of Clinical Research,University of Berne, Berne, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Frick
authors.forename: Alex
authors.initials: A
authors.lastname: Odermatt
authors.forename: Ke
authors.initials: K
authors.lastname: Zen
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Mandell
authors.forename: Heather
authors.initials: H
authors.lastname: Edens
authors.forename: Reto
authors.initials: R
authors.lastname: Portmann
authors.forename: Luca
authors.initials: L
authors.lastname: Mazzucchelli
authors.forename: David L
authors.initials: DL
authors.lastname: Jaye
authors.forename: Charles A
authors.initials: CA
authors.lastname: Parkos
mesh_terms: D001665:Binding Sites; D039521:CD11c Antigen / Q000378:metabolism*; D018821:CD18 Antigens / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D016167:Integrin alphaXbeta2 / Q000378:metabolism*; D018799:Intercellular Adhesion Molecule-1 / Q000737:chemistry* / Q000378:metabolism*; D008024:Ligands; D018716:Molecular Mimicry; D009504:Neutrophils / Q000378:metabolism; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary
chemical_list: D039521:CD11c Antigen; D018821:CD18 Antigens; D016167:Integrin alphaXbeta2; D008024:Ligands; D019151:Peptide Library; D010455:Peptides; D018799:Intercellular Adhesion Molecule-1