Crystal Structure of the Heterotrimeric Integrin-Binding Region of Laminin-111

Abstract

SummaryLaminins are cell-adhesive glycoproteins that are essential for basement membrane assembly and function. Integrins are important laminin receptors, but their binding site on the heterotrimeric laminins is poorly defined structurally. We report the crystal structure at 2.13 Å resolution of a minimal integrin-binding fragment of mouse laminin-111, consisting of ∼50 residues of α1β1γ1 coiled coil and the first three laminin G-like (LG) domains of the α1 chain. The LG domains adopt a triangular arrangement, with the C terminus of the coiled coil situated between LG1 and LG2. The critical integrin-binding glutamic acid residue in the γ1 chain tail is surface exposed and predicted to bind to the metal ion-dependent adhesion site in the integrin β1 subunit. Additional contacts to the integrin are likely to be made by the LG1 and LG2 surfaces adjacent to the γ1 chain tail, which are notably conserved and free of obstructing glycans.

Chlorination and oxidation of the extracellular matrix protein laminin and basement membrane extracts by hypochlorous acid and myeloperoxidase

“…Mapping of the detected modifications onto a complete 3D structure cannot be accomplished at present, as only a small number of partial structures are available. A recently structure (PDB entry: 5MC9) [83] contains the coordinates of the xLG1-3 domains, as well as~50 residues of the coiled coil (α1β1γ1). These sequences contain 20 Tyr, of which 11 were identified as chlorination targets, 14 Met, of which 7 were detected as sulfoxides, and 4 Trp, with 3 of these detected as oxidised species (Fig.…”

“…The detection of modifications to (surface-exposed) Tyr 2415 is of particular interest as it is situated close to Glu 1605 (indicated in brown, in Fig. 11, panel A), which is essential for interactions with integrins [83][84][85]. Modification of this residue, and possibly others nearby, may therefore affect integrin binding to laminins, and hence cell binding to the ECM [4,85].…”

Mechanistic basis for the recognition of laminin-511 by α6β1 integrin

“…Pulido et al . ( 13 ) noted that the LG1 and LG2 surfaces on either side of the γ1-tail are more highly conserved than that of LG3, implying that the residues involved in integrin binding lie within the highly conserved surfaces. Our exhaustive disulfide cross-link screening with Cys-substituted LM511E8 and α6β1 integrin showed that the γ1-tail came into close contact with and cross-linked with integrin β1 residue 133 near the β1-MIDAS even in the absence of γ1E1607.…”

Structural Basis for the Initiation of Glycosaminoglycan Biosynthesis by Human Xylosyltransferase 1

“…DNA coding for residues 232-959 of human XT1 was amplified from a cDNA clone (Dharmacon) using Q5 polymerase (New England Biolabs) and ligated into a modified pCEP-Pu vector that adds a TEV protease-cleavable His-tag at the N-terminus of the secreted protein ( Pulido et al., 2017 ). The vector was transfected into FreeStyle 293-F cells (Thermo Fisher Scientific) using linear polyethylimine (MW 25,000; Polysciences).…”