一个与I组内核RNA结合的tRNA合成酶合因子的结构
Paul J Paukstelis1, Jui-Hui Chen, Elaine Chase
1Institute for Cellular and Molecular Biology, Department of Chemistry and Biochemistry, and Section of Molecular Genetics and Microbiology, School of Biological Sciences, University of Texas at Austin, Austin, Texas 78712, USA.
Nature
|January 4, 2008
概括
蛋白质进化以协助RNA剪接,从RNA世界过渡到RNP世界. 一个新的晶体结构揭示了蛋白质 (CYT-18) 如何结合I组内子,帮助它们的拼接和进化.
科学领域:
- 进化生物学 进化生物学
- 结构生物学 结构生物学
- 分子生物学分子生物学
背景情况:
- "RNA世界"假设表明,RNA最初执行了遗传和催化功能.
- 现代生物学特点是 ribozymes 和蛋白质-RNA 复合体 (RNPzymes),表明从RNA到蛋白质主导地位的过渡.
- I 组内子,RNA 催化剂,通常作为蛋白质稳定的 RNP 酶起作用.
研究的目的:
- 阐明由蛋白质介导的I组内拼接的结构基础.
- 了解蛋白质在RNA催化过程中的进化适应.
- 为从RNA世界向RNP世界过渡提供洞察力.
主要方法:
- 确定了一种4.5-Å联合晶体结构的I组内离子 ribozyme与一个截断的拼接活性蛋白 (CYT-18) 结合.
- 分析了内部RNA和同位体蛋白质之间的结构相互作用.
- 我们比较了CYT-18的内结合表面与非剪接的细菌氨基-tRNA合成酶.
主要成果:
- 组I内子结合于同质基CYT-18蛋白的两个子单元.
- 在CYT-18上有一种新的RNA结合表面,稳定了内子的催化核.
- 在CYT-18中的调整,包括小插入,促进I组内核结合和拼接,使其与非拼接的TyrRS区别开来.
结论:
- CYT-18的结构揭示了它促进I组内拼接的机制.
- 这些发现说明了蛋白质对RNA剪接的多步进化适应.
- 这项研究提供了一个结构性的观点,即蛋白质如何在生命早期逐渐取代RNA功能.
相关概念视频
RNA Splicing
Splicing is the process by which eukaryotic RNA is edited before its translation into protein. The RNA strand transcribed from eukaryotic DNA is called the primary transcript. The primary transcripts that become mRNAs are called precursor messenger RNAs (pre-mRNAs). Eukaryotic pre-mRNA contains alternating sequences of exons and introns. Exons are nucleotide sequences that code for proteins, whereas introns are the non-coding regions. In RNA splicing, introns are removed and exons are bonded...
RNA Splicing
Splicing is the process by which eukaryotic RNA is edited before its translation into protein. The RNA strand transcribed from eukaryotic DNA is called the primary transcript. The primary transcripts that become mRNAs are called precursor messenger RNAs (pre-mRNAs). Eukaryotic pre-mRNA contains alternating sequences of exons and introns. Exons are nucleotide sequences that code for proteins, whereas introns are the non-coding regions. In RNA splicing, introns are removed and exons are bonded...
Transfer 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...
Alternative RNA Splicing
Alternative RNA splicing is the regulated splicing of exons and introns to produce different mature mRNAs from a single pre-mRNA. Unlike in constitutive splicing where a single gene produces a single type of mRNA, alternative splicing allows an organism to produce multiple proteins from a single gene and plays an important role in protein diversity.
There are five types of alternative RNA splicing that vary in the ways the pre-mRNA segments are removed or retained in the mature mRNA. The first...
There are five types of alternative RNA splicing that vary in the ways the pre-mRNA segments are removed or retained in the mature mRNA. The first...
Alternative RNA Splicing
Alternative RNA splicing is the regulated splicing of exons and introns to produce different mature mRNAs from a single pre-mRNA. Unlike in constitutive splicing where a single gene produces a single type of mRNA, alternative splicing allows an organism to produce multiple proteins from a single gene and plays an important role in protein diversity.
There are five types of alternative RNA splicing that vary in the ways the pre-mRNA segments are removed or retained in the mature mRNA. The first...
There are five types of alternative RNA splicing that vary in the ways the pre-mRNA segments are removed or retained in the mature mRNA. The first...
Transfer 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...


