在缺少密码子的情况下,在核糖体中通过tmRNA和SmpB进行解码
Cajetan Neubauer1, Reynald Gillet, Ann C Kelley
1Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK.
概括
细菌停滞的核糖体被转移信使RNA (tmRNA) 和SmpB蛋白所拯救. 晶体结构揭示了SmpB如何模仿tRNA和mRNA,在不破坏正常翻译的情况下促进救援.
科学领域:
- 细菌分子生物学 细菌分子生物学
- 核糖体功能和救援机制
- 结构生物学是结构生物学.
背景情况:
- 在细菌翻译过程中,核糖体可以在截断的信使RNAs (mRNAs) 的末端停滞.
- 转移信使RNA (tmRNA) 和SmpB蛋白形成一个复合体来拯救这些停滞不前的核糖体.
- 通过tmRNA-SmpB促进救援并与核糖体相互作用的精确机制尚未完全理解.
研究的目的:
- 阐明tmRNA-SmpB系统的核糖体救援功能的结构基础.
- 了解SmpB在救援过程中如何与核糖体和tmRNA相互作用.
- 解释tmRNA-SmpB系统在拯救停滞的核糖体中的特异性.
主要方法:
- 在X射线晶体学.
- 确定一个tmRNA片段,SmpB,延长因子Tu和核糖体复合体的晶体结构.
- 高分辨率结构分析在3.2安格斯特罗姆.
主要成果:
- 晶体结构揭示了tmRNA片段,SmpB和延长因子Tu与细菌核糖体的复杂结合.
- 已经证明SmpB可以模仿转移RNA (tRNA) 抗环和信使RNA (mRNA) 序列的功能.
- 这种仿真促进了解码过程,即使在核糖体的A位点中没有mRNA编码子.
结论:
- tmRNA-SmpB系统采用一种独特的机制,其中SmpB作为tRNA和mRNA组件的替代品.
- 这种结构洞察力解释了核糖体救援是如何有效调解的.
- 这些发现澄清了为什么tmRNA-SmpB救援系统不会干扰正典翻译过程.
相关概念视频
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The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
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