从"缺失环节"家族A RAGL转位子的识别来了解RAG进化
Eliza C Martin1, Lorlane Le Targa2, Louis Tsakou-Ngouafo2
1Department of Immunobiology, Yale School of Medicine, New Haven, CT 06520-8011, USA.
Molecular biology and evolution
|October 18, 2023
概括
在无脊椎动物如半带动物和皮动物中发现的RAGL-A转位子,是RAG1-RAG2重组酶进化的关键中间体,对于脊椎动物的适应性免疫是必不可少的.
科学领域:
- 进化生物学是进化的生物学.
- 分子生物学分子生物学
- 基因组学就是基因组学.
背景情况:
- RAG1-RAG2 (RAG) 重组酶对于脊椎动物的适应性免疫是至关重要的.
- 据信RAG是从一种无脊椎动物RAG-like (RAGL) 转基因酶通过"分子化"进化而来的.
- 对于RAGL转体的进化史和中间形式的了解很少,特别是RAGL-A家族.
研究的目的:
- 调查无脊椎动物中完整RAGL-A转位子的存在和特征.
- 了解RAGL-A转体和RAG重组酶之间的进化关系.
- 确定RAG的化过程中的关键进化步骤.
主要方法:
- 基因组分析以确定Ptychodera flava和皮动物中的完整RAGL-A转位子.
- 对RAG1L-A和RAG2L-A蛋白序列及其功能域的生物信息预测.
- 对RAGL-A转位子序列与RAG和RAGL-B转位子进行比较分析.
- 功能性测试,以测试RAG2L-A酸性链区域在RAG介导转移上的抑制活性.
主要成果:
- 在P. flava和几种皮体基因组中确定了完整的RAGL-A转体.
- 预测RAG1L-A和RAG2L-A蛋白质表现出RAG和RAGL-B转基因酶特征的马赛克.
- RAGL-A转位子终端反向重复 (TIR) 结合了RAGL-B TIR和RAG重组信号序列的特征.
- RAG2L-A蛋白质具有能够抑制RAG转换的酸性链区域.
结论:
- RAGL-A转体子在RAG复合酶的进化过程中是一个关键的中间体.
- 之前认为是脊椎动物特有的RAG2酸性链,起源于无脊椎动物.
- 这些发现将重点转移到其他适应,因为RAG在脊椎动物的化中至关重要.
相关概念视频
Overview of Transposition and Recombination
15.6K
Transposons make up a significant part of genomes of various organisms. Therefore, it is believed that transposition played a major evolutionary role in speciation by changing genome sizes and modifying gene expression patterns. For example, in bacteria, transposition can lead to conferring antibiotic resistance. Movement of transposable elements within the genetic pool of pathogenic bacteria can aid in transfer of antibiotic-resistant genetic elements. In eukaryotes, transposons can carry out...
15.6K
LTR Retrotransposons
17.5K
LTR retrotransposons are class I transposable elements with long terminal repeats flanking an internal coding region. These elements are less abundant in mammals compared to other class I transposable elements. About 8 percent of human genomic DNA comprises LTR retrotransposons. Some of the common examples of LTR retrotransposons are Ty elements in yeast and Copia elements in Drosophila.
The internal coding region of LTR retrotransposons and their mechanism of transposition closely resembles a...
The internal coding region of LTR retrotransposons and their mechanism of transposition closely resembles a...
17.5K
Non-LTR Retrotransposons
11.5K
As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...
11.5K
DNA-only Transposons
14.5K
DNA-only transposons are called autonomous transposons since they code for the enzyme transposase that is required for the transposition mechanism. Insertion of transposons can alter gene functions in multiple ways. They can mutate the gene, alter gene expression by introducing a novel promoter or insulator sequence, introduce new splice sites, and change the mRNA transcripts produced, or remodel chromatin structure.
The donor site from where the transposon is excised is either degraded or...
The donor site from where the transposon is excised is either degraded or...
14.5K
piRNA - Piwi-interacting RNAs
6.9K
PIWI-interacting RNAs, or piRNAs, are the most abundant short non-coding RNAs. More than 20,000 genes have been found in humans that code for piRNAs while only 2000 genes have been found for miRNAs. piRNAs can act at the transcriptional and post-transcriptional levels and have a vital role in silencing transposable elements present in germ cells. They are also involved in epigenetic silencing and activation. Previously, they were thought to function only in germ cells but new evidence suggests...
6.9K
Transposons
39
Transposons, or "jumping genes," are small mobile genetic elements (MGEs) that range from 700 to 40,000 base pairs in length. They are found in all organisms and can move within the same chromosome or transfer to different chromosomes. In some cases, transposons can also jump between different host DNA molecules, such as plasmids or viruses, contributing to genetic variability.Barbara McClintock first discovered these mobile genetic elements in the 1940s while studying maize genetics, and she...
39


