Biochemical and Structural Characterization of Lysophosphatidic Acid Binding by a Humanized Monoclonal Antibody
Biochemical and Structural Characterization of Lysophosphatidic Acid Binding by a Humanized Monoclonal Antibody
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DOI：
10.1016/j.jmb.2011.02.061
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发表时间：
2011-05-06
影响因子：
5.6
通讯作者：
Huxford, Tom
中科院分区：
文献类型：
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作者：
Fleming, Jonathan K.;Wojciak, Jonathan M.;Huxford, Tom
溶血磷脂酸（LPA）是甘油磷脂代谢的常见产物，是重要的信号转导介质。异常高的LPA浓度伴随着多种疾病状态。因此，治疗这些疾病的一种潜在方法是将识别并结合LPA作为其抗原的抗体用于治疗。我们确定了抗LPA抗体（LT3015） Fab片段在无抗原形式下的x射线晶体结构，分辨率为2.15埃，与两个LPA同型（14:0和18:2）复合物的x射线晶体结构分别为1.98和2.51埃。抗原结合位点的可变CDR（互补决定区）环在自由晶体结构和抗原结合晶体结构中采用几乎相同的构象。晶体学模型显示，LT3015抗体利用重链和轻链CDR环与LPA抗原的甘油磷酸头基团形成8个氢键网络。头部基团几乎完全不与溶剂接触，而碳氢化合物尾部部分暴露于溶剂。一般来说，抗原结合位点氨基酸残基的突变会破坏LPA的结合。然而，在结构的基础上战略性地选择特定突变的引入可以积极影响LPA的结合亲和力。最后，这些结构阐明了抗脂质抗体结合结构简单且看似不受约束的靶分子所表现出的精致特异性。(c) 2011 Elsevier Ltd.版权所有。
Lysophosphatidic acid (LPA) is a common product of glycerophospholipid metabolism and an important mediator of signal transduction. Aberrantly high LPA concentrations accompany multiple disease states. One potential approach for treatment of these diseases, therefore, is the therapeutic application of antibodies that recognize and bind LPA as their antigen. We have determined the X-ray crystal structure of an anti-LPA antibody (LT3015) Fab fragment in its antigen-free form to 2.15 angstrom resolution and in complex with two LPA isotypes (14:0 and 18:2) to resolutions of 1.98 and 2.51 angstrom, respectively. The variable CDR (complementarity-determining region) loops at the antigen binding site adopt nearly identical conformations in the free and antigen-bound crystal structures. The crystallographic models reveal that the LT3015 antibody employs both heavy- and light-chain CDR loops to create a network of eight hydrogen bonds with the glycerophosphate head group of its LPA antigen. The head group is almost completely excluded from contact with solvent, while the hydrocarbon tail is partially solvent-exposed. In general, mutation of amino acid residues at the antigen binding site disrupts LPA binding. However, the introduction of particular mutations chosen strategically on the basis of the structures can positively influence LPA binding affinity. Finally, these structures elucidate the exquisite specificity demonstrated by an anti-lipid antibody for binding a structurally simple and seemingly unconstrained target molecule. (c) 2011 Elsevier Ltd. All rights reserved.