3hi6
Crystal structure of intermediate affinity I domain of integrin LFA-1 with the Fab fragment of its antibody AL-57Crystal structure of intermediate affinity I domain of integrin LFA-1 with the Fab fragment of its antibody AL-57
Structural highlights
FunctionITAL_HUMAN Integrin alpha-L/beta-2 is a receptor for ICAM1, ICAM2, ICAM3 and ICAM4. It is involved in a variety of immune phenomena including leukocyte-endothelial cell interaction, cytotoxic T-cell mediated killing, and antibody dependent killing by granulocytes and monocytes. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe activity of integrin LFA-1 (alpha(L)beta(2)) to its ligand ICAM-1 is regulated through the conformational changes of its ligand-binding domain, the I domain of alpha(L) chain, from an inactive, low-affinity closed form (LA), to an intermediate-affinity form (IA), and then finally, to a high-affinity open form (HA). A ligand-mimetic human monoclonal antibody AL-57 (activated LFA-1 clone 57) was identified by phage display to specifically recognize the affinity-upregulated I domain. Here, we describe the crystal structures of the Fab fragment of AL-57 in complex with IA, as well as in its unligated form. We discuss the structural features conferring AL-57's strong selectivity for the high affinity, open conformation of the I domain. The AL-57-binding site overlaps the ICAM-1 binding site on the I domain. Furthermore, an antibody Asp mimics an ICAM Glu by forming a coordination to the metal-ion dependent adhesion site (MIDAS). The structure also reveals better shape complementarity and a more hydrophobic interacting interface in AL-57 binding than in ICAM-1 binding. The results explain AL-57's antagonistic mimicry of LFA-1's natural ligands, the ICAM molecules. Structural basis of activation-dependent binding of ligand-mimetic antibody AL-57 to integrin LFA-1.,Zhang H, Liu JH, Yang W, Springer T, Shimaoka M, Wang JH Proc Natl Acad Sci U S A. 2009 Oct 27;106(43):18345-50. Epub 2009 Sep 23. PMID:19805116[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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