概括
通过Escherichia coli Tn3溶解酶进行特定位点的重组,需要直接重复重组位点 (res位点). 这种酶是一种1型拓酶,独特地产生单个相互连接的连锁酶,详细说明DNA动态.
科学领域:
- 分子生物学分子生物学
- 酶学 是一种酶学.
- 遗传学 是一个遗传学.
背景情况:
- 特定地点的重组对于遗传元素动态至关重要.
- 转位子溶解酶调解这些重组事件.
- 了解溶解酶机制为DNA拓和操纵提供了洞察力.
研究的目的:
- 为了研究大肠杆菌Tn3溶解酶的催化和机械性质.
- 阐明解决酶介导的DNA重组和放松的要求.
- 根据其观察到的酶活性,提出一种解决酶作用的模型.
主要方法:
- 清理大肠杆菌Tn3溶解酶的纯化.
- 在体外再组合试验中,使用具有不同位配置的超卷塑料.
- 用DNA放松测试来评估拓酶活性.
- 对再组合产品的分析,包括catenanes.
主要成果:
- 净化溶解酶有效地重组了具有直接重复的溶解位点的超卷塑体.
- Resolvase表现出严格的网站特异性,仅在直接重复的网站上起作用.
- 倒置或单个res站点,即使在很近的地方,也没有支持重组或放松.
- 再组合产品仅仅是单独相互关联的连锁物.
- 溶解酶作为1型拓酶起作用,产生单链断裂.
结论:
- 解决方案需要特定的定位和活动地点的近距离.
- 该酶的特性表明一种涉及DNA路径定义和精确链交换的机制.
- 一个模型涉及二维解析酶子单元的结合和搜索res网站解释观察到的活动.
- 溶解酶的1型拓酶活性决定了一次一次的DNA断裂机制.
相关概念视频
02:02DNA Topoisomerases
Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
02:31Homologous 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...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
02:13Overview 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...
02:53Conservative Site-specific Recombination and Phase Variation
Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The recognition sites for Cre recombinase called LoxP...
02:31Homologous 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...