NMR and mutagenesis evidence for an I domain allosteric site that regulates lymphocyte function-associated antigen 1 ligand binding

Huth, Jeffrey R.; Olejniczak, Edward T.; Mendoza, Renaldo; Liang, Heng; Harris, Edith A. S.; Lupher, Mark L.; Wilson, Amy E.; Fesik, Stephen W.; Staunton, Donald E.

doi:10.1073/pnas.97.10.5231

Cited by 161 publications

(172 citation statements)

References 49 publications

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“…Glu-310 in ␣ L , is indispensable for Mn 2ϩ -induced activation of ␤ 2 integrins (32,33,44). Mutation of either the metal-coordinating MIDAS residue Ser-114 in the ␤ 2 I domain or Glu-310 in the ␣ L I domain C-terminal linker totally abolished Mn 2ϩ -induced ICAM-1 binding (Fig.…”

Section: The Activating Effect Of Compound 4 Is Inhibited By Compoundmentioning

confidence: 99%

A Small Molecule Agonist of an Integrin, αLβ2

Yang

Carman

Kim

et al. 2006

Journal of Biological Chemistry

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Integrins are a large family of ␣/␤ heterodimeric cell surface receptors that mediate cell-cell and cell-extracellular matrix adhesion and transduce signals bidirectionally across the plasma membrane. Integrin ␣ L ␤ 2 (lymphocyte function associated antigen-1 (LFA-1)) 5 belongs to the ␤ 2 integrin subfamily and is constitutively expressed on all leukocytes. ␣ L ␤ 2 remains in a low affinity state in resting lymphocytes and undergoes dramatic conformational change during lymphocyte activation, which greatly increases its binding affinity for its ligands intercellular adhesion molecule -1, -2, and -3 (ICAM-1, -2, and -3). Regulation of ␣ L ␤ 2 activation is pivotal for controlling leukocyte trafficking and immune responses in health and diseases (1-3).␣ L ␤ 2 is an important pharmaceutical target for treating autoimmune and inflammatory diseases (4 -8). A humanized antibody to ␣ L ␤ 2 that blocks its binding to the ligand ICAM-1 has been approved by the FDA for treatment of psoriasis, a T cellmediated autoimmune disease of the skin (9, 10). Furthermore, small molecule antagonists of ␣ L ␤ 2 have been discovered and are in development (11)(12)(13)(14)(15)(16)(17).␣ L ␤ 2 contains two von Willebrand factor-type A domains, the inserted (I) domains in the ␣ L and the ␤ 2 subunits (18 -20). Both ␣ L I and ␤ 2 I domains have a Rossman fold (i.e. a central ␤-sheet surrounded by ␣-helices) with a metal ion-dependent adhesion site (MIDAS) formed by ␤-␣ loops at the "top" face of the domain (20 -23). In ligand binding the Mg 2ϩ ion in the MIDAS of the ␣ L I domain coordinates directly to a Glu residue that is in the center of the ligand binding sites in domain 1 of 24). The affinity of the ␣ L I domain for ICAMs is regulated by downward axial displacement of its C-terminal ␣7 helix, which is conformationally linked to reshaping of MIDAS loops and increases affinity for ligand by up to 10,000-fold (25, 26). During activation, the ␤ I domain undergoes similar ␣7 helix downward axial movement, which is induced by the swing out of the hybrid domain (27)(28)(29)(30). 6 Previous data suggested that when activated, the ␤ 2 I domain binds (through the Mg 2ϩ in its MIDAS) to the Glu residue (Glu-310) in the C-terminal linker of the ␣ L I domain, exerts a downward pull on its ␣7 helix, and thereby activates the ␣ L I domain (Fig. 1A) (32, 33).Two distinct classes of small molecule antagonists of ␣ L ␤ 2 have been developed as anti-inflammatory agents. One group of antagonists binds the hydrophobic pocket underneath the ␣7 helix of the ␣ L I domain (e.g. LFA703 or BIRT377), blocks the downward axial movement of the ␣7 helix, and inhibits ligand binding of ␣ L ␤ 2 allosterically by stabilizing the ␣ L I domain in the low affinity conformation (11)(12)(13)(14)34). These antagonists are called ␣ I allosteric inhibitors. The other group of antagonists appears to bind to the ␤ 2 I domain MIDAS near a key regulatory interface with the ␣ L I domain, blocking communication of conformational change to the ␣ L I domain while at the same time ac...

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Section: The Activating Effect Of Compound 4 Is Inhibited By Compoundmentioning

confidence: 99%

A Small Molecule Agonist of an Integrin, αLβ2

Yang

Carman

Kim

et al. 2006

Journal of Biological Chemistry

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“…Thus far, structures for the ␣L I domain have been determined only in the closed conformation (15-17); however, on binding to ICAM-1, NMR signals are altered for ␤-strand 6, the C-terminal ␣-helix 6, and the loop connecting them, as well as residues in the MIDAS (32) for ICAM-1. Although the I domain is implicated as an important site for ligand binding in those integrins that contain it, we found that the isolated wild-type ␣L I domain did not support K562 transfectant binding to immobilized ICAM-1.…”

Section: Locking the Open And Closed Conformations Of The I Domain Withmentioning

confidence: 99%

An isolated, surface-expressed I domain of the integrin αLβ2 is sufficient for strong adhesive function when locked in the open conformation with a disulfide bond

Shimaoka

Ferzly

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

127

152

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“…The structure of the ␣L I domain has been determined only in the closed conformation (18); however, there is direct evidence for conformational change (19), and we hypothesized that the ␣L I domain might exist in an open conformation similar to that seen in crystal structures for ␣M (10) and ␣2 (12) I domains. We have introduced disulfide bonds into the ␣L I domain to lock it in the open or closed conformation and examined the consequences for cell adhesion (20,21).…”

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confidence: 99%