Complex Structure of Engineered Modular Domains Defining Molecular Interaction between ICAM-1 and Integrin LFA-1

Abstract

Intermolecular contacts between integrin LFA-1 (αLβ2) and ICAM-1 derive solely from the integrin αL I domain and the first domain (D1) of ICAM-1. This study presents a crystal structure of the engineered complex of the αL I domain and ICAM-1 D1. Previously, we engineered the I domain for high affinity by point mutations that were identified by a directed evolution approach. In order to examine αL I domain allostery between the C-terminal α7-helix (allosteric site) and the metal-ion dependent adhesion site (active site), we have chosen a high affinity variant without mutations directly influencing either the position of the α7-helix or the active sites. In our crystal, the αL I domain was found to have a high affinity conformation to D1 with its α7-helix displaced downward away from the binding interface, recapitulating a current understanding of the allostery in the I domain and its linkage to neighboring domains of integrins in signaling. To enable soluble D1 of ICAM-1 to fold on its own, we also engineered D1 to be functional by mutations, which were found to be those that would convert hydrogen bond networks in the solvent-excluded core into vdW contacts. The backbone structure of the β-sandwich fold and the epitope for I domain binding of the engineered D1 were essentially identical to those of wild-type D1. Most deviations in engineered D1 were found in the loops at the N-terminal region that interacts with human rhinovirus (HRV). Structural deviation found in engineered D1 was overall in agreement with the function of engineered D1 observed previously, i.e., full capacity binding to αL I domain but reduced interaction with HRV.

Acute-phase concentrations of soluble fibrinogen inhibit neutrophil adhesion under flow conditions in vitro through interactions with ICAM-1 and MAC-1 (CD11b/CD18)

“…sFg binds to IgG‐like domain 1 on ICAM‐1 . This is the same binding site on ICAM‐1 that is necessary for interaction with LFA‐1 . In contrast, binding of MAC‐1 to ICAM‐1 is unlikely to be affected by sFg binding to ICAM‐1, as this interaction is mediated by a distant MAC‐1‐binding site on ICAM‐1, IgG‐like domain 3 .…”

“Live” Nanomaterials Process Biomimetic Recognition and Assembly In Vivo

“…[72] More specifically, the α L I domain in integrin recognizes and assembles with the first domain (D1) in ICAM-1. [73] The recognition and assembly is able to effectively eliminate inflammatory. [15,74,75] The membrane of natural WBCs was utilized to encapsulate cargoes for the treatment of inflammatory precisely (Figure 1b).…”

“…[ 72 ] More specifically, the α L I domain in integrin recognizes and assembles with the first domain (D1) in ICAM‐1. [ 73 ] The recognition and assembly is able to effectively eliminate inflammatory. [ 15,74,75 ]…”

Isolation of L I domain mutants mediating firm cell adhesion using a novel flow-based sorting method

“…The pulley-like motion of this helix causes rearrangements in the metal ion-dependant adhesion side (MIDAS), leading to the dramatic increase in affinity for ICAM-1. While the a L I domain has not been crystallized in the 'open,' high affinity conformation, I domain mutants have been engineered to mimic this state (Shimaoka et al, 2003;Kang et al, 2012). One method used two cysteine mutations to lock the I domain in the open, high-affinity conformation by regulating the position of the a7 helix.…”

“…Additionally, a number of other double cysteine mutants were created to lock the I domain in a range of intermediate affinity conformations (Shimaoka et al, 2003). More recent work takes advantage of a mutation isolated from a library of I domain mutants sorted for high affinity using soluble ligand binding to impart the high-affinity state (Jin et al, 2006;Kang et al, 2012).…”