键形成破坏了在核糖体上的Shine-Dalgarno相互作用的稳定
Sotaro Uemura1, Magdalena Dorywalska, Tae-Hee Lee
1Department of Physics, Stanford University, Stanford, California 94305, USA.
Nature
|March 23, 2007
概括
闪光-达尔加诺序列在键形成之前增强了核糖体-mRNA结合的稳定性. 在第一个键形成后,这种相互作用会减弱,在翻译过程中促进核糖体的运动.
科学领域:
- 分子生物学分子生物学
- 生物物理学的生物物理.
- 遗传学 是一个遗传学.
背景情况:
- 核糖体将信使RNA (mRNA) 转化为蛋白质序列.
- 核糖体-mRNA相互作用对于翻译启动和延长至关重要.
- 闪亮-达尔加诺 (SD) 序列对于细菌的翻译启动至关重要.
研究的目的:
- 使用光学子测量单个核糖体复合体和mRNA之间的破裂力.
- 调查Shine-Dalgarno (SD) 序列在核糖体-mRNA复合体稳定性中的作用.
- 为了确定键的形成如何影响核糖体-mRNA相互作用的强度.
主要方法:
- 开发了一种光学 tweezer 试验,以量化单核糖核糖核糖核糖核酸破裂力.
- 在带有SD序列和没有SD序列的核糖体复合体中比较破裂力.
- 使用氨基酸tRNA (Phe-tRNA(Phe)) 和基tRNA模拟物 (N-乙-Phe-tRNA(Phe)) 来模仿不同的翻译阶段.
主要成果:
- 删除SD序列显著减少了当Phe-tRNA (Phe) 在A位点时的核糖体-mRNA破裂力.
- SD序列的存在增强了体-mRNA复合体在键形成之前的稳定性.
- 第一个键的形成,被N-乙-Phe-tRNA(Phe) 模仿,在含有SD和缺乏SD的mRNA中类似地减弱了破裂力.
结论:
- 在翻译启动过程中,SD序列相互作用显著促进了核糖体-mRNA复合体的稳定性.
- 第一个键的形成破坏了SD相互作用的稳定性,削弱了核糖体对mRNA的控制.
- 这种减弱对于在早期的翻译步骤中在mRNA沿线促进核糖体转位至关重要.
相关概念视频
Protein Organization
Overview
Peptide Bonds
A peptide bond covalently attaches amino acids through a dehydration reaction. One amino acid's carboxyl group and another amino acid's amino group combine, releasing a water molecule. The resulting bond is the peptide bond. The products that such linkages form are peptides. As more amino acids join this growing chain, the resulting chain is a polypeptide. Each polypeptide has a free amino group at one end. This end has the N-terminal, or the amino-terminal, and the other end has a free...
Termination of Translation
The large ribosomal subunit has several important structures essential to translation. These include the peptidyl transferase center (PTC) - which is the site where the peptide bond is formed - and a large, internal, water-filled tube through which the nascent polypeptide moves. This latter structure is called the Peptide Exit Tunnel, and it begins at the PTC and spans the body of the large ribosomal subunit. During translation, as the nascent polypeptide chain is synthesized, it passes through...
Protein Organization
Proteins are polymers of amino acid residues. They are versatile and responsible for different cellular functions, including DNA replication, molecular transport, catalysis, and structural support. Proteins have a hierarchical structure comprising at least three levels of organization: primary, secondary, and tertiary structure. Some large proteins have a quaternary structure where individual protein subunits are linked together.
The primary structure of a protein is its amino acid sequence.
The primary structure of a protein is its amino acid sequence.
Translation in Prokaryotes
Prokaryote translation is a complex, highly coordinated process that converts genetic information from mRNA into functional proteins. It involves three stages: initiation, elongation, and termination, each facilitated by specific molecular components.Initiation of TranslationThe process begins with the assembly of the ribosomal subunits and initiation factors on the mRNA. In bacteria, the 30S ribosomal subunit recognizes the Shine-Dalgarno sequence in the mRNA, a conserved region upstream of...
Translational Regulation
Translational regulation in prokaryotes ensures efficient protein synthesis by controlling ribosome access to mRNA. This regulation is mediated by secondary RNA structures, including translational riboswitches, RNA thermometers, and small RNAs (sRNAs), which respond to intracellular and environmental signals to modulate gene expression.Translational RiboswitchesRiboswitches in the leader region of mRNAs can regulate translation by altering the accessibility of the Shine-Dalgarno (SD) sequence,...


