含瓜的ssDNA和RNA诱导SAMHD1的二度和四度结构形式
Benjamin Orris1, Min Woo Sung2, Shridhar Bhat1
1Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine 725 North Wolfe Street Baltimore, MD 21205, USA.
Nucleic acids research
|November 6, 2023
概括
脱氧核酸三酸三酸酶1 (SAMHD1) 在单链DNA和RNA中结合瓜. 关氨酸结合会诱导SAMHD1的二重化或四重化,影响其酶活性.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 结构生物学 结构生物学
背景情况:
- 含有脱氧核酸三酸三酸酶1 (SAMHD1) 的四重 SAM 和 HD 域调节细胞dNTP水平.
- SAMHD1与DNA复制叉,DNA修复焦点,ssRNA和端粒相互作用,需要核酸结合.
- SAMHD1的寡合状态可能会调节其功能.
研究的目的:
- 为了研究SAMHD1如何与核酸结合.
- 为了确定SAMHD1-核酸相互作用的结构基础.
- 了解核酸结合如何影响SAMHD1的寡合体状态和酶活性.
主要方法:
- 低温电子显微镜 (cryo-EM) 用于确定结构.
- 生物化学试验用于研究酶活性和核酸结合.
主要成果:
- SAMHD1使用其关氨酸特异性的A1激活器位点在ssDNA和ssRNA中结合关氨酸核酸.
- 一个单一的关氨酸诱导SAMHD1二分化,而两个或更多的关氨酸间隔约20个核酸诱导四分化.
- 与ssRNA结合的四重体SAMHD1的冷EM结构揭示了ssRNA桥接两个SAMHD1二元体.
- 与ssRNA结合的四聚酶对dNTPase和RNase活性是不活跃的.
结论:
- 核酸结合,特别是对瓜的结合,是SAMHD1寡合状态的关键调节者.
- 在ssRNA结合时观察到的构造变化和四聚酶的失活,为SAMHD1调节提供了洞察力.
- 这项研究阐明了SAMHD1调节的新机制,通过关氨酸依赖的寡合化和核酸相互作用.
相关概念视频
01:03Single-Strand DNA Binding Proteins
14.1K
For successful DNA replication, the unwinding of double-stranded DNA must be accompanied by stabilization and protection of the separated single strands of the DNA. This crucial task is performed by single-strand DNA-binding (SSB) proteins. They bind to the DNA in a sequence-independent manner, which means that the nitrogenous bases of the DNA need not be present in a specific order for binding of SSB proteins to it. The binding of SSB proteins straightens single-stranded DNA (ssDNA) and makes...
14.1K
02:31Homologous Recombination
50.6K
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...
50.6K
02:37Restarting Stalled Replication Forks
5.8K
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,...
5.8K
02:04Fixing Double-strand Breaks
12.6K
The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
12.6K
00:55DNA Helicases
21.4K
DNA unwinding helicase enzymes are a type of motor protein. Motor proteins can translocate along filaments or polymers using energy generated from ATP hydrolysis. Helicases are involved in all the important cellular processes where DNA unwinding is required, such as DNA replication, repair, recombination, and transcription. They are present in all living organisms, but vary in their structure, function, and mechanism of action. For example, in prokaryotes, DnaB helicase binds and translocates...
21.4K
01:05Maxam-Gilbert Sequencing
11.2K
In the same year as the discovery of the Sanger sequencing method, another group of scientists, Allan Maxam and Walter Gilbert, demonstrated their chemical-cleavage method for DNA sequencing. The Maxam-Gilbert method relies on using different chemicals that can cleave the DNA sequence at specific sites, the separation of resulting DNA fragments of variable size using electrophoresis, and deciphering the DNA sequence from the resulting gel bands.
Challenges of the Maxam-Gilbert Method
The...
Challenges of the Maxam-Gilbert Method
The...
11.2K