一种含有4.5SRNA的大肠杆菌核糖蛋白类似于哺乳动物信号识别粒子
M A Poritz1, H D Bernstein, K Strub
1Department of Biochemistry and Biophysics, University of California Medical School, San Francisco 94143-0448.
概括
研究人员确定了一种细菌信号识别粒子 (SRP) 复合体,涉及Ffh蛋白和4.5SRNA,对于蛋白质出口至关重要. 突变导致热冲击和细胞外缺陷,影响大肠杆菌中的蛋白质转位.
科学领域:
- 分子生物学分子生物学
- 细胞生物学 细胞生物学
- 微生物学 微生物学
背景情况:
- 信号识别粒子 (SRP) 对于哺乳动物细胞中的蛋白质输出至关重要.
- 细菌中依赖于SRP的转位机制仍然没有表征.
- 序列分析显示了SRP组件的细菌同类物:大肠杆菌ffh基因 (SRP54同类物) 和ffs基因 (4.5SRNA,类似于7SLRNA).
研究的目的:
- 研究细菌中类似SRP机器的存在和功能.
- 描述Ffh蛋白与4.5SRNA之间的相互作用.
- 为了确定破坏这种细菌SRP复合物的细胞后果.
主要方法:
- 序列比较以识别同源基因.
- 使用抗血清对Ffh蛋白进行免疫沉以检测复合物.
- 酶分析测试RNA结合和功能.
- 使用可诱导促进体和主导突变 (4.5S RNAdl1) 的基因操纵.
- 在诱导突变条件下对细菌细胞的表型分析.
主要成果:
- 在大肠杆菌中,Ffh蛋白和4.5SRNA形成了一个复合体.
- 4.5SRNA与SRP54结合,可以在体外取代7SLRNA.
- 主导4.5SRNA突变 (4.5SRNAdl1) 的表达是致命的.
- 诱导的4.5SRNAdl1导致热冲击反应,细胞质异常蛋白质的积累,以及β-lactamase转位受损.
- 观察到细胞外缺陷 (内外膜分离);其他蛋白质转位不受影响.
结论:
- 大肠杆菌具有类似于SRP的复合体,由Ffh和4.5SRNA组成.
- 这种复合体对于细菌蛋白质出口和细胞完整性至关重要.
- 综合体的破坏会导致热效应,包括热冲击和细胞外异常.
更多相关视频
08:56In Situ Detection of Ribonucleoprotein Complex Assembly in the C. elegans Germline using Proximity Ligation Assay
Published on: May 5, 2020
08:58RNA Fluorescence in situ Hybridization (FISH) to Visualize Microbial Colonization and Infection in Caenorhabditis elegans Intestines
Published on: July 27, 2022
相关概念视频
Bacterial Signaling
Bacterial signaling can occur within bacteria (intracellular) or between bacteria (intercellular). At times, a group of bacteria behaves like a community. To achieve this, they engage in quorum sensing, the perception of higher cell density that causes changes in gene expression. Quorum sensing involves both extracellular and intracellular signaling. The signaling cascade starts with a molecule called an autoinducer (AI). Individual bacteria produce AIs that move out of the bacterial cell...
Yeast Signaling
Yeasts are single-celled organisms, but unlike bacteria, they are eukaryotes (cells with a nucleus). Cell signaling in yeast is similar to signaling in other eukaryotic cells. A ligand, such as a protein or a small molecule released from a yeast cell, attaches to a receptor on the cell surface. The binding stimulates second-messenger kinases to activate or inactivate transcription factors that further regulate gene expression. Many of the yeast intracellular signaling cascades have similar...
Nuclear Export of mRNA
Before mRNAs are exported to the cytoplasm, it is crucial to check each mRNA for structural and functional integrity. Eukaryotic cells use several different mechanisms, collectively known as mRNA surveillance, to look for irregularities in mRNAs. Irregular or aberrant mRNA are rapidly degraded by various enzymes. If a defective mRNA escapes the surveillance, it would be translated into a protein which would either be non-functional or not function properly. One of the primary irregularities in...
Signal Sequences and Sorting Receptors
Signal sequences are short amino acid sequences that guide newly synthesized proteins to their proper location within the cell. Classical signal sequences are fifteen to sixty amino acids long and present at the N-terminus of a polypeptide chain. Each signal sequence has a conserved segment of basic residues towards their N terminus, a hydrophobic core, and a C-terminus rich in polar residues. The C-terminus also contains a signal cleavage site and features a -3 -1 sequence motif. The -3-1...
Nuclear Localization Signals and Import
Proteins targeted to the nucleus carry short stretches of amino acid sequences called the nuclear localization signal or NLS. Classical nuclear localization signals are of two types: monopartite and bipartite NLS. Monopartite classical NLS (cNLS) consists of a single cluster of 4-8 amino acids. Bipartite cNLS consists of two clusters of 2-3 amino acids and a 9-12 residue long proline-rich linker bridging the two clusters. Signal clusters are rich in positively charged amino acids such as...
Gram-negative Bacterial Protein Secretion Systems
Gram-negative bacteria utilize sophisticated protein secretion systems to transport proteins across their double-membrane envelope into the extracellular environment or host cells. Based on their mechanism of action, these systems are classified into one-step and two-step pathways.One-Step Secretion Systems (Types I, III, IV, and VI)One-step secretion systems bypass the periplasm entirely, forming a continuous channel that spans both the inner and outer membranes:Type I Secretion System (T1SS):...
