Di Carluccio Cristina, Soriano-Maldonado Pablo, Berni Francesca, de Haas Carla J C, Temming A Robin, Hendriks Astrid, Ali Sara, Molinaro Antonio, Silipo Alba, van Sorge Nina M, van Raaij Mark J, Codee Jeroen D C, Marchetti Roberta
Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126Naples, Italy.
Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Calle Darwin 3, 28049Madrid, Spain.
ACS Cent Sci. 2022 Oct 26;8(10):1383-1392. doi: 10.1021/acscentsci.2c00125. Epub 2022 Aug 17.
Wall teichoic acids (WTAs) are glycopolymers decorating the surface of Gram-positive bacteria and potential targets for antibody-mediated treatments against , including methicillin-resistant (MRSA) strains. Through a combination of glycan microarray, synthetic chemistry, crystallography, NMR, and computational studies, we unraveled the molecular and structural details of fully defined synthetic WTA fragments recognized by previously described monoclonal antibodies (mAbs 4461 and 4497). Our results unveiled the structural requirements for the discriminatory recognition of α- and β-GlcNAc-modified WTA glycoforms by the complementarity-determining regions (CDRs) of the heavy and light chains of the mAbs. Both mAbs interacted not only with the sugar moiety but also with the phosphate groups as well as residues in the ribitol phosphate (RboP) units of the WTA backbone, highlighting their significant role in ligand specificity. Using elongated WTA fragments, containing two sugar modifications, we also demonstrated that the internal carbohydrate moiety of α-GlcNAc-modified WTA is preferentially accommodated in the binding pocket of mAb 4461 with respect to the terminal moiety. Our results also explained the recently documented cross-reactivity of mAb 4497 for β-1,3/β-1,4-GlcNAc-modified WTA, revealing that the flexibility of the RboP backbone is crucial to allow positioning of both glycans in the antibody binding pocket.
壁磷壁酸（WTAs）是修饰革兰氏阳性菌表面的糖聚合物，是针对包括耐甲氧西林金黄色葡萄球菌（MRSA）菌株在内的细菌进行抗体介导治疗的潜在靶点。通过聚糖微阵列、合成化学、晶体学、核磁共振和计算研究相结合的方法，我们揭示了先前描述的单克隆抗体（单克隆抗体4461和4497）所识别的完全确定的合成WTA片段的分子和结构细节。我们的结果揭示了单克隆抗体重链和轻链的互补决定区（CDRs）对α-和β-氨基葡萄糖修饰的WTA糖型进行区分识别的结构要求。两种单克隆抗体不仅与糖部分相互作用，还与磷酸基团以及WTA主链的核糖醇磷酸（RboP）单元中的残基相互作用，突出了它们在配体特异性中的重要作用。使用含有两种糖修饰的延长WTA片段，我们还证明，相对于末端部分，α-氨基葡萄糖修饰的WTA的内部碳水化合物部分优先容纳在单克隆抗体4461的结合口袋中。我们的结果还解释了最近记录的单克隆抗体4497对β-1,3/β-1,4-氨基葡萄糖修饰的WTA的交叉反应性，揭示了RboP主链的灵活性对于使两种聚糖定位在抗体结合口袋中至关重要。
