Huadong Research Institute for Medicine and Biotechniques, Nanjing 210002, China.
College of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu, 210009, China.
Biomed Res Int. 2019 Jul 9;2019:9297129. doi: 10.1155/2019/9297129. eCollection 2019.
is an obligate intracellular bacterium that is responsible for far-eastern spotted fever. Surface-exposed proteins (SEPs) play important roles in its pathogenesis. Previous work identified a ribosomal protein RpsB as an SEP by biotin-avidin affinity, a seroreactive antigen, and a diagnostic candidate protein, indicating that it might play an important role in the pathogenesis of rickettsiae. However, in the absence of other evidence, its subcellular location of being surface-exposed was puzzling because ribosomal proteins are located in the cytoplasm. In the present study, the subcellular location of RpsB was analyzed with bioinformatics tools coupled with immunoelectron microscopy. The adhesion ability of RpsB was evaluated by protein microarray and cellular ELISA. Consequently, different bioinformatics tools gave different location predication results. Thus, RpsB was found in the cytoplasma and inner and outer membranes of by transmission electron microscopy. Protein microarray and cellular ELISA showed that RpsB binds to the host cell surface and its adhesion ability was even stronger than the known adhesin Adr1. In conclusion, RpsB was visually and directly shown for the time to be an SEP of rickettsiae and might be an important ligand and adhesin of rickettsiae. Its roles in pathogenesis warrant further study.
是一种专性细胞内细菌，可引起远东斑疹热。表面暴露蛋白（SEPs）在其发病机制中发挥重要作用。先前的工作通过生物素-亲和素亲和力、血清反应性抗原和诊断候选蛋白鉴定出核糖体蛋白 RpsB 为 SEP，表明它可能在立克次体的发病机制中发挥重要作用。然而，在缺乏其他证据的情况下，它表面暴露的亚细胞位置令人费解，因为核糖体蛋白位于细胞质中。在本研究中，通过生物信息学工具结合免疫电子显微镜分析了 RpsB 的亚细胞位置。通过蛋白质微阵列和细胞 ELISA 评估了 RpsB 的粘附能力。结果，不同的生物信息学工具给出了不同的位置预测结果。因此，透射电子显微镜显示 RpsB 存在于细胞质以及和的内膜和外膜中。蛋白质微阵列和细胞 ELISA 表明，RpsB 与宿主细胞表面结合，其粘附能力甚至强于已知的粘附素 Adr1。总之，RpsB 被直观地直接证明为立克次体的 SEP，可能是立克次体的重要配体和粘附素。其在发病机制中的作用值得进一步研究。
