Department of Biology, University of Ottawa, Ontario K1N 6N5, Canada.
Ottawa Institute of Systems Biology, Ontario K1H 8M5, Canada.
G3 (Bethesda). 2017 May 5;7(5):1607-1615. doi: 10.1534/g3.117.039305.
The 3' end of the small ribosomal RNAs (ssu rRNA) in bacteria is directly involved in the selection and binding of mRNA transcripts during translation initiation via well-documented interactions between a Shine-Dalgarno (SD) sequence located upstream of the initiation codon and an anti-SD (aSD) sequence at the 3' end of the ssu rRNA. Consequently, the 3' end of ssu rRNA (3'TAIL) is strongly conserved among bacterial species because a change in the region may impact the translation of many protein-coding genes. and differ in their 3' ends of ssu rRNA, being GAUC3' in and GAUCUCU3' or GAUCUCUA3' in Such differences in 3'TAIL lead to species-specific SDs (designated SD for and SD for ) that can form strong and well-positioned SD/aSD pairing in one species but not in the other. Selection mediated by the species-specific 3'TAIL is expected to favor SD against SD in , but favor SD against SD in Among well-positioned SDs, SD is used more in than in , and SD more in than in Highly expressed genes and genes of high translation efficiency tend to have longer SDs than lowly expressed genes and genes with low translation efficiency in both species, but more so in than in Both species overuse SDs matching the bolded part of the 3'TAIL shown above. The 3'TAIL difference contributes to the host specificity of phages.
细菌的小核糖体 RNA (ssu rRNA) 的 3' 端直接参与翻译起始过程中 mRNA 转录本的选择和结合，这是通过起始密码子上游的 Shine-Dalgarno (SD) 序列和 ssu rRNA 3' 端的反 SD (aSD) 序列之间的已有充分文献记载的相互作用实现的。因此，ssu rRNA 的 3' 端（3'TAIL）在细菌物种中高度保守，因为该区域的变化可能会影响许多编码蛋白质基因的翻译。 和 在它们的 ssu rRNA 的 3' 端不同，分别为 GAUC3' 和 GAUCUCU3' 或 GAUCUCUA3'。这种 3'TAIL 的差异导致物种特异性的 SD（分别命名为 和 的 SD），它们可以在一个物种中形成强而定位良好的 SD/aSD 配对，但在另一个物种中则不能。由物种特异性 3'TAIL 介导的选择预计会在 中有利于 SD 对抗 SD，但有利于 SD 对抗 SD 在 中。在定位良好的 SD 中， 在 中比 在 中使用得更多， 在 中比 在 中使用得更多。在这两个物种中，高表达基因和高翻译效率的基因的 SD 比低表达基因和低翻译效率的基因的 SD 更长，但 在 中比 在 中更为明显。这两个物种都过度使用与上述加粗的 3'TAIL 匹配的 SD。3'TAIL 的差异有助于噬菌体的宿主特异性。
