一种大肠杆菌氨基酸-tRNA合成酶可以在体内替代酵母线粒体酶的功能
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Cell
|November 20, 1987
概括
研究人员通过表达一种带电转移RNA (tRNA) 的细菌酶,恢复了酵母的呼吸. 这表明,尽管有序列差异,但细菌酶可以识别和与酵母氨酸tRNA功能.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 生物化学 生物化学
背景情况:
- 线粒体功能依赖于特定的氨基-tRNA合成酶来进行蛋白质合成.
- 酵母线粒体铁基-tRNA合成酶 (TyrRS) 对于呼吸至关重要.
- 呼吸缺陷的酵母菌株为研究线粒体蛋白质功能提供了一个模型.
研究的目的:
- 为了研究大肠杆菌tRNA合成酶 (EcTyrRS) 与Saccharomyces cerevisiae线粒体的功能兼容性.
- 确定 EcTyrRS 是否可以在缺乏内源性线粒体 TyrRS 的酵母中挽救呼吸系统缺陷.
- 评估线粒体进口序列在EcTyrRS.的向和功能中的作用.
主要方法:
- 用酵母线粒体进口序列构建编码EcTyrRS的基因融合.
- 在呼吸不足的酵母菌株中表达融合基因.
- 通过生物化学和遗传分析评估呼吸功能和蛋白质定位.
主要成果:
- 在缺乏功能性线粒体 TyrRS.的酵母中,EcTyrRS 融合蛋白的表达恢复了呼吸.
- 融合蛋白被成功地导入酵母线粒体.
- 由酵母衍生序列介导的线粒体进口对于拯救呼吸系统缺陷至关重要.
- 尽管有序列分歧,但EcTyrRS在线粒体内有效地充电了酵母氨酸tRNA.
结论:
- 细菌的tRNA合成酶可以在酵母线粒体内发挥作用.
- 线粒体进口信号在各个物种中保持和功能.
- 这项研究表明,tRNA合成酶的基质识别能力比以前假设的更广泛.
- 这项研究提供了对跨物种蛋白向和线粒体功能补充的见解.
相关概念视频
02:36Transfer RNA Synthesis
One of the unique features of tRNA is the presence of modified bases. In some tRNAs, modified bases account for nearly 20% of the total bases in the molecule. Altogether, these unusual bases protect the tRNA from enzymatic degradation by RNases.
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
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02:47Ribozymes
The term ribozyme is used for RNA that can act as an enzyme. Ribozymes are mainly found in selected viruses, bacteria, plant organelles, and lower eukaryotes. Ribozymes were first discovered in 1982 when Tom Cech’s laboratory observed Group I introns acting as enzymes. This was shortly followed by the discovery of another ribozyme, Ribonulcease P, by Sid Altman’s laboratory. Both Cech and Altman received the Nobel Prize in chemistry in 1989 for their work on ribozymes.
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02:36Transfer RNA Synthesis
One of the unique features of tRNA is the presence of modified bases. In some tRNAs, modified bases account for nearly 20% of the total bases in the molecule. Altogether, these unusual bases protect the tRNA from enzymatic degradation by RNases.
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
02:26tRNA Activation
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...