Surface plasmon resonance study on functional significance of clustered organization of lectin-like oxidized LDL receptor (LOX-1)

• Published in: Biochimica et biophysica acta Vol. 1814; no. 2; pp. 345 - 354
• Main Authors: Ohki, Izuru, Amida, Hirokazu, Yamada, Risato, Sugihara, Mamoru, Ishigaki, Tomoko, Tate, Shin-ichi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2011
• Subjects: Amino Acid Substitution; Atherosclerosis; Dimerization; Humans; In Vitro Techniques; Kinetics; Lipoproteins, LDL - metabolism; LOX-1; Models, Molecular; Mutagenesis, Site-Directed; Oxidized LDL; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - metabolism; Protein Binding; Protein Structure, Quaternary; Protein Structure, Tertiary; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Scavenger Receptors, Class E - chemistry; Scavenger Receptors, Class E - genetics; Scavenger Receptors, Class E - metabolism; Surface Plasmon Resonance; CD; RU; ECD; βME; apoE; LOX-1; apoB; AcLDL; NMR; SPR; CTLD; HAEC; DC-SIGN; Oxidized LDL; Atherosclerosis; Surface plasmon resonance; OxLDL; HSQC
• ISSN: 1570-9639; 0006-3002; 1878-1454
• DOI: 10.1016/j.bbapap.2010.10.006

Lectin-like oxidized low-density lipoprotein (OxLDL) receptor 1 (LOX-1) is the major OxLDL receptor of vascular endothelial cells and is involved in an early step of atherogenesis. LOX-1 exists as a disulfide-linked homodimer on the cell surface, which contains a pair of the ligand-binding domains (CTLD; C-type lectin-like domain). Recent research using living cells has suggested that the clustered state of LOX-1 dimer on the cell is functionally required. These results questioned how LOX-1 exists on the cell to achieve OxLDL binding. In this study, we revealed the functional significance of the clustered organization of the ligand-binding domain of LOX-1 with surface plasmon resonance. Biotinylated CTLD was immobilized on a streptavidin sensor chip to make CTLD clusters on the surface. In this state, the CTLD had high affinity for OxLDL with a dissociation constant ( K D) in the nanomolar range. This value is comparable to the K D measured for LOX-1 on the cell. In contrast, a single homodimeric LOX-1 extracellular domain had lower affinity for OxLDL in the supra-micromolar range of K D. Monomeric CTLD showed marginal binding to OxLDL. In combination with the analyses on the loss-of-binding mutant W150A, we concluded that the clustered organization of the properly formed homodimeric CTLD is essential for the strong binding of LOX-1 to OxLDL. [Display omitted] ► Clustered CTLD showed affinity to OxLDL as found for LOX-1 on plasma membrane. ► LOX-1 binds to OxLDL in a multivalent manner. ► Properly formed CTLD dimer structure is required in the LOX-1 binding to OxLDL.