Molecular Basis of the Recognition of Nephronectin by Integrin α8β1

• Sato, Yuya

• Uemura, Toshihiko

• Morimitsu, Keisuke

• Sato, Ryoko

• Manabe, Ri-ichiroh

• Takagi, Junichi

• Yamada, Masashi

• Sekiguchi, Kiyotoshi

Abstract

This research was originally published in the Journal of Biological Chemistry. Yuya Sato, Toshihiko Uemura, Keisuke Morimitsu, Ryoko Sato-Nishiuchi, Ri-ichiroh Manabe, Junichi Takagi, Masashi Yamada and Kiyotoshi Sekiguchi. Molecular Basis of the Recognition of Nephronectin by Integrin α8β1. J. Biol. Chem. 2009; 284: 14524-14536 © the American Society for Biochemistry and Molecular Biology

Integrin α8β1 interacts with a variety of Arg-Gly-Asp (RGD)-containing ligands in the extracellular matrix. Here, we examined the binding activities of α8β1 integrin toward a panel of RGD-containing ligands. Integrin α8β1 bound specifically to nephronectin with an apparent dissociation constant of 0.28 ± 0.01 nm, but showed only marginal affinities for fibronectin and other RGD-containing ligands. The high-affinity binding to α8β1 integrin was fully reproduced with a recombinant nephronectin fragment derived from the RGD-containing central “linker” segment. A series of deletion mutants of the recombinant fragment identified the LFEIFEIER sequence on the C-terminal side of the RGD motif as an auxiliary site required for high-affinity binding to α8β1 integrin. Alanine scanning mutagenesis within the LFEIFEIER sequence defined the EIE sequence as a critical motif ensuring the high-affinity integrin-ligand interaction. Although a synthetic LFEIFEIER peptide failed to inhibit the binding of α8β1 integrin to nephronectin, a longer peptide containing both the RGD motif and the LFEIFEIER sequence was strongly inhibitory, and was ∼2,000-fold more potent than a peptide containing only the RGD motif. Furthermore, trans-complementation assays using recombinant fragments containing either the RGD motif or LFEIFEIER sequence revealed a clear synergism in the binding to α8β1 integrin. Taken together, these results indicate that the specific high-affinity binding of nephronectin to α8β1 integrin is achieved by bipartite interaction of the integrin with the RGD motif and LFEIFEIER sequence, with the latter serving as a synergy site that greatly potentiates the RGD-driven integrin-ligand interaction but has only marginal activity to secure the interaction by itself.

Journal

• Journal of Biological Chemistry

  Journal of Biological Chemistry 284 (21), 14524-14536, 2009-05

  American Society for Biochemistry and Molecular Biology

Details

• CRID: 1050018218948878336
• NII Article ID: 120006585493
• NII Book ID: AA1202441X
• ISSN: 1083351X
• HANDLE: 11094/71424
• Text Lang: en
• Article Type: journal article
• Data Source:
  • IRDB
  • CiNii Articles