没有tRNA内核的真核生物
Ambro van Hoof1, Tokiko Furata2, Swathi Arur2
1The University of Texas Health Science Center at Houston; ambro.van.hoof@uth.tmc.edu.
RNA (New York, N.Y.)
|August 22, 2025
概括
一些线虫已经丢失了转移RNA (tRNA) 内子. 一个物种,Levipalatum texanum,完全缺乏tRNA内核和tRNA内核酶,提供了对内核进化和拼接机制的见解.
科学领域:
- 基因组学
- 分子生物学
- 进化生物学
背景情况:
- 细胞基因组通常含有结合体内核,tRNA内核和XBP1mRNA内核.
- 在真核生物中,tRNA 内核和tRNA 内核酶被认为是普遍存在的.
- 在Metazoa中,Tyr-GUA,Ile-UAU和Leu-CAA tRNA中的内子被保存.
研究的目的:
- 在真核基因组中研究tRNA内核的存在和保存.
- 识别已丢失tRNA内核的物种并分析相关的基因组变化.
- 了解tRNA内核损失的进化影响.
主要方法:
- 对线虫物种进行比较基因组分析.
- 在特定的tRNA (Tyr-GUA,Ile-UAU,Leu-CAA) 中识别内子存在/不存在.
- 相关遗传元素的分析,包括tRNA脱氨酶和tRNA结合酶.
主要成果:
- 一些线虫物种已经从Tyr-GUA和Ile-UAU tRNA中丢失了内核.
- 莱维帕拉图姆德克萨南完全没有tRNA内核.
- L. texanum也缺乏tRNA内核酶,但保留了tRNA连接酶和XBP1内核,显示了A-C不匹配和tRNA脱氨酶三倍化等适应.
结论:
- 在一些线虫物种中发生的tRNA内核损失并不像以前想象的那样罕见.
- 莱维帕拉图姆 (Levipalatum texanum) 是一个独特的模型生物,用于研究tRNA拼接,XBP1拼接和tRNA修饰的不同功能.
- 这一发现挑战了真核生物中tRNA内核和tRNA内核酶的普遍性,并为进化适应提供了洞察力.
相关概念视频
02:07Organization of Genes
69.3K
Overview
69.3K
02:36Transfer RNA Synthesis
12.2K
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...
12.2K
01:32RNA Splicing
56.9K
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...
56.9K
00:58Genomic DNA in Eukaryotes
47.7K
Eukaryotes have large genomes compared to prokaryotes. To fit their genomes into a cell, eukaryotic DNA is packaged extraordinarily tightly inside the nucleus. To achieve this, DNA is tightly wound around proteins called histones, which are packaged into nucleosomes that are joined by linker DNA and coil into chromatin fibers. Additional fibrous proteins further compact the chromatin, which is recognizable as chromosomes during certain phases of cell division.
47.7K
01:35Pre-mRNA Processing: Modification of pre-mRNA Ends
9.8K
In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or pre-mRNA to distinguish it from mature mRNA.
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps...
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps...
9.8K
00:58Eukaryotic RNA Polymerases
6.8K
6.8K