グループIIのイントロン移動は,標的DNAにプリムされた逆転写によって発生します
S Zimmerly1, H Guo, P S Perlman
1Department of Molecular Genetics, Ohio State University, Columbus 43210-1292, USA.
Cell
|August 25, 1995
まとめ
酵母のような移動性グループIIイントロンは,酵母のようなものです.
科学分野:
- 分子生物学は分子生物学である.
- 遺伝学 遺伝学とは
- バイオケミストリー バイオケミストリー
背景:
- 移動群IIイントロンは,逆転写写酵素をコードする遺伝要素である.
- 彼らは,ホーミングと呼ばれるプロセスを通して,サイト特異的にイントロンレスアレルに挿入することが知られている.
研究 の 目的:
- イーストミトコンドリアDNA (mtDNA) 群IIイントロン aI2.2.のホーミングのインビトロメカニズムを解明する.
- ホーミングプロセスにおける逆転写酵素タンパク質とイントロンRNAの役割を調査する.
主な方法:
- インビトロ実験では,酵母mtDNA群IIイントロンaI2.2.を用いて実施した.
- サイト固有のエンドヌクレアース活性と逆転写を分析した.
- DNAエンドヌクレアース活性に対するリバーストランスクリプタゼタンパク質とRNAの必要性を評価した.
主要な成果:
- 酵母mtDNA群IIイントロンaI2のホーミングは,受容体DNAの二重鎖の断裂で逆転写によって発生します.
- サイト固有のエンドヌクレアスは受容体のDNA鎖を分割し,イントロンのプレ-mRNAの逆転写をプライミングします.
- DNA内核酵素は,aI2逆転写酵素タンパク質とaI2RNAの両方を活性化するために必要とします.
結論:
- この研究は,逆転写とDNA分裂を含むIIグループイントロンホーミングの詳細なメカニズムを明らかにしています.
- この発見は,移動性IIグループ・イントロンが,保存された逆転写メカニズムにより,核非長い末端のリピートレトロトランポゾンとテロメラーゼの祖先である可能性があることを示唆している.
関連する概念動画
Homologous Recombination
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
Overview of Transposition and Recombination
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...
DNA-only Transposons
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...
LTR Retrotransposons
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...
Non-LTR Retrotransposons
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...
piRNA - Piwi-interacting RNAs
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...


