NovImmune SA, 1228 Plan Les Ouates, Switzerland.
J Biol Chem. 2012 Jan 6;287(2):1458-67. doi: 10.1074/jbc.M111.253658. Epub 2011 Oct 31.
Dual-specific antibodies are characterized by an antigen-combining site mediating specific interactions with two different antigens. We have generated five dual-specific single chain variable fragments (scFv) that neutralize the activity of the two chemokines, CXCL9 and CXCL10, to bind to their receptor CXCR3. To better understand how these dual-specific scFvs bind these two chemokines that only share a 37% sequence identity, we mapped their epitopes on human CXCL9 and CXCL10 and identified serine 13 (Ser(13)) as a critical residue. It is conserved between the two chemokines but not in the third ligand for CXCR3, CXCL11. Furthermore, Ser(13) is exposed in the tetrameric structure of CXCL10, which is consistent with our finding that the scFvs are able to bind to CXCL9 and CXCL10 immobilized on glycosaminoglycans. Overall, the data indicate that these dual-specific scFvs bind to a conserved surface involved in CXCR3 receptor interaction for CXCL10 and CXCL9. Thus, structural mimicry between the two targets is likely to be responsible for the observed dual specificity of these antibody fragments.
双特异性抗体的特点是抗原结合位点介导与两种不同抗原的特异性相互作用。我们已经生成了五种能够中和两种趋化因子 CXCL9 和 CXCL10 活性的双特异性单链可变片段 (scFv)，以与它们的受体 CXCR3 结合。为了更好地理解这些双特异性 scFv 如何结合这两种仅共享 37%序列同一性的趋化因子，我们在人源 CXCL9 和 CXCL10 上绘制了它们的表位，并确定丝氨酸 13 (Ser(13)) 是一个关键残基。它在两种趋化因子中是保守的，但在 CXCR3 的第三个配体 CXCL11 中不是。此外，Ser(13)在 CXCL10 的四聚体结构中暴露，这与我们的发现一致，即 scFv 能够结合固定在糖胺聚糖上的 CXCL9 和 CXCL10。总体而言，数据表明这些双特异性 scFv 结合 CXCL10 和 CXCL9 与 CXCR3 受体相互作用涉及的保守表面。因此，两个靶标之间的结构模拟可能是这些抗体片段观察到的双特异性的原因。
