As an indispensable molecular machine universal in all living organisms, the ribosome has been selected by evolution to be the natural target of many antibiotics and small-molecule inhibitors. High-resolution structures of pathogen ribosomes are crucial for understanding the general and unique aspects of translation control in disease-causing microbes. With cryo-electron microscopy technique, we have determined structures of the cytosolic ribosomes from two human parasites, Trichomonas vaginalis and Toxoplasma gondii, at resolution of 3.2–3.4 Å. Although the ribosomal proteins from both pathogens are typical members of eukaryotic families, with a co-evolution pattern between certain species-specific insertions/extensions and neighboring ribosomal RNA (rRNA) expansion segments, the sizes of their rRNAs are sharply different. Very interestingly, rRNAs of T. vaginalis are in size comparable to prokaryotic counterparts, with nearly all the eukaryote-specific rRNA expansion segments missing. These structures facilitate the dissection of evolution path for ribosomal proteins and RNAs, and may aid in design of novel translation inhibitors.

中文翻译：

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人类寄生虫阴道毛滴虫和弓形虫80S核糖体的低温-EM结构

作为核糖体在所有活生物体中普遍存在的必不可少的分子机器，核糖体经进化被选为许多抗生素和小分子抑制剂的天然靶标。病原体核糖体的高分辨率结构对于理解致病微生物中翻译控制的一般性和独特性至关重要。用冷冻电子显微镜技术，我们确定了来自两个人类寄生虫阴道毛滴虫和弓形虫的胞质核糖体的结构，分辨率为3.2-3.4Å。尽管两种病原体的核糖体蛋白都是真核生物家族的典型成员，但在某些特定物种的插入/延伸和邻近的核糖体RNA（rRNA）扩增片段之间具有共同进化的模式，但它们的rRNA大小却截然不同。非常有趣的是 阴道锥虫的rRNA大小可与原核类似物相提并论，几乎缺少所有真核生物特异的rRNA扩增片段。这些结构有助于解剖核糖体蛋白和RNA的进化路径，并可能有助于设计新型翻译抑制剂。