哺乳动物核糖体43S预启动复合物的结构与扫描因子DHX2929结合
Yaser Hashem1, Amedee des Georges, Vidya Dhote
1Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
Cell
|May 28, 2013
概括
对于真核转换至关重要的43S预启动复合体,用DHX29.2进行了结构分析. 这揭示了对mRNA扫描和启动至关重要的新型相互作用和方向,特别是在结构化的mRNA上.
科学领域:
- 分子生物学分子生物学
- 结构生物学 结构生物学
- 生物化学 生物化学
背景情况:
- 细胞翻译启动是一个复杂的过程,涉及43S预启动复合体.
- 这种复杂的组合对于精确的蛋白质合成至关重要.
- 结构化信使RNAs (mRNAs) 对翻译启动提出了独特的挑战.
研究的目的:
- 为了确定哺乳动物DHX29-bound 43S预启动复合物的结构.
- 阐明DHX29在结构化mRNA的翻译启动中的作用.
- 为了深入了解真核生物特有的翻译机制.
主要方法:
- 低温电子显微镜 (cryo-EM) 的分辨率为11.6 Å.
- 结合DHX29.29的43S预启动复合物的结构分析.
主要成果:
- 该结构揭示了真核启动因子 (eIF) 2和40S核糖体子单元之间的相互作用.
- 甲基尼化启动子甲基因转移RNA (Met-tRNAi(Met)) 观察到一个意想不到的P/I方向 (eP/I).
- DHX29围绕40S子单元的螺旋16结合,eIF3的核心位于子单元的背面.
结论:
- 这项研究提供了DHX29结合的43S复合体的高分辨率结构.
- 它提供了关于DHX29在翻译启动过程中的作用机制的见解.
- 这些发现揭示了转化启动的真核生物特异性方面,特别是对于具有挑战性的mRNA结构.
相关概念视频
Ribosomal RNA Synthesis
Ribosome synthesis is a highly complex and coordinated process involving more than 200 assembly factors. The synthesis and processing of ribosomal components occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells.
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Ribosomal RNA Synthesis
Ribosome synthesis is a highly complex and coordinated process involving more than 200 assembly factors. The synthesis and processing of ribosomal components occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells.
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Initiation of Translation
Initiating translation is complex because it involves multiple molecules. Initiator tRNA, ribosomal subunits, and eukaryotic initiation factors (eIFs) are all required to assemble on the initiation codon of mRNA. This process consists of several steps that are mediated by different eIFs.
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
Ribosomes
Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that synthesize large quantities of protein—such as secretory cells in the human pancreas—can contain millions of ribosomes.
Ribosome Structure and Assembly
Ribosomes are composed of ribosomal RNA (rRNA) and proteins. In eukaryotes, rRNA is transcribed from genes in the nucleolus—a part of the nucleus that specializes in ribosome production. Within...
Ribosome Structure and Assembly
Ribosomes are composed of ribosomal RNA (rRNA) and proteins. In eukaryotes, rRNA is transcribed from genes in the nucleolus—a part of the nucleus that specializes in ribosome production. Within...
Ribosomes
Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that synthesize large quantities of protein—such as secretory cells in the human pancreas—can contain millions of ribosomes.
Ribosome Structure and Assembly
Ribosomes are composed of ribosomal RNA (rRNA) and proteins. In eukaryotes, rRNA is transcribed from genes in the nucleolus—a part of the nucleus that specializes in ribosome production. Within...
Ribosome Structure and Assembly
Ribosomes are composed of ribosomal RNA (rRNA) and proteins. In eukaryotes, rRNA is transcribed from genes in the nucleolus—a part of the nucleus that specializes in ribosome production. Within...
Leaky Scanning
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...


