PDF(Pubmed)
Abstract：
Neisserial adhesin A (NadA) is a meningococcal surface protein included as recombinant antigen in 4CMenB, a protein-based vaccine able to induce protective immune responses against Neisseria meningitidis serogroup B (MenB). Although NadA is involved in the adhesion/invasion of epithelial cells and human myeloid cells, its function in meningococcal physiology is still poorly understood. To clarify the role played by NadA in the host-pathogen interaction, we sought to identify its cellular receptors. We screened a protein microarray encompassing 2,846 human and 297 mouse surface/secreted recombinant proteins using recombinant NadA as probe. Efficient NadA binding was revealed on the paired sialic acid-binding immunoglobulin-type lectins receptors 5 and 14 (Siglec-5 and Siglec-14), but not on Siglec-9 therein used as control. The interaction was confirmed by biochemical tools with the determination of the KD value in the order of nanomolar and the identification of the NadA binding site by hydrogen-deuterium exchange coupled to mass spectrometry. The N-terminal domain of the Siglec-5 that recognizes the sialic acid was identified as the NadA binding domain. Intriguingly, exogenously added recombinant soluble Siglecs, including Siglec-9, were found to decorate N. meningitidis surface in a NadA-dependent manner. However, Siglec-5 and Siglec-14 transiently expressed in CHO-K1 cells endorsed NadA binding and increased N. meningitidis adhesion/invasion while Siglec-9 did not. Taken together, Siglec-5 and Siglec-14 satisfy all features of NadA receptors suggesting a possible role of NadA in the acute meningococcal infection.IMPORTANCEBacteria have developed several strategies for cell colonization and immune evasion. Knowledge of the host and pathogen factors involved in these mechanisms is crucial to build efficacious countermoves. Neisserial adhesin A (NadA) is a meningococcal surface protein included in the anti-meningococcus B vaccine 4CMenB, which mediates adhesion to and invasion of epithelial cells. Although NadA has been shown to bind to other cell types, like myeloid and endothelial cells, it still remains orphan of a defined host receptor. We have identified two strong NadA interactors, Siglec-5 and Siglec-14, which are mainly expressed on myeloid cells. This showcases that NadA is an additional and key player among the Neisseria meningitidis factors targeting immune cells. We thus provide novel insights on the strategies exploited by N. meningitidis during the infection process, which can progress to a severe illness and death.
摘要：
奈瑟氏菌粘附素A（NadA）是一种脑膜炎球菌表面蛋白，作为4CMenB中的重组抗原，一种基于蛋白质的疫苗，能够诱导针对脑膜炎奈瑟菌血清群B（MenB）的保护性免疫应答。尽管NadA参与上皮细胞和人类骨髓细胞的粘附/侵袭，其在脑膜炎球菌生理学中的功能仍然知之甚少。为了阐明NadA在宿主-病原体相互作用中的作用，我们试图确定它的细胞受体。我们使用重组NadA作为探针筛选了包含2,846个人和297小鼠表面/分泌重组蛋白的蛋白质微阵列。在配对的唾液酸结合免疫球蛋白型凝集素受体5和14（Siglec-5和Siglec-14）上揭示了有效的NadA结合，但没有在Siglec-9上用作对照。通过生化工具，以纳摩尔的顺序确定KD值，并通过氢-氘交换与质谱联用来鉴定NadA结合位点，从而确认了相互作用。识别唾液酸的Siglec-5的N末端结构域被鉴定为NadA结合结构域。有趣的是，外源添加的重组可溶性Siglecs，包括Siglec-9在内，被发现以NadA依赖的方式装饰脑膜炎奈瑟球菌表面。然而,在CHO-K1细胞中瞬时表达的Siglec-5和Siglec-14认可NadA结合并增加脑膜炎奈瑟球菌粘附/侵袭,而Siglec-9没有。一起来看,Siglec-5和Siglec-14满足NadA受体的所有特征,表明NadA在急性脑膜炎球菌感染中的可能作用。重要细菌已经开发了几种用于细胞定植和免疫逃避的策略。了解这些机制中涉及的宿主和病原体因素对于建立有效的对策至关重要。奈瑟氏菌粘附素A（NadA）是一种脑膜炎球菌表面蛋白，包含在抗脑膜炎球菌B疫苗4CMenB中，介导上皮细胞的粘附和侵袭。尽管NadA已被证明与其他细胞类型结合，如髓样细胞和内皮细胞，它仍然是确定的宿主受体的孤儿。我们已经确定了两个强大的NadA交互者，Siglec-5和Siglec-14主要在骨髓细胞上表达。这表明NadA是针对免疫细胞的脑膜炎奈瑟菌因子中的额外和关键参与者。因此，我们对脑膜炎奈瑟菌在感染过程中利用的策略提供了新的见解，会发展成严重的疾病和死亡。
