転写レギュレータであるEscherichia coliのNikRRにおけるニッケル特異的反応
Sharon Leitch1, Michael J Bradley, Jessica L Rowe
1Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Journal of the American Chemical Society
|April 3, 2007
まとめ
エシェリキア・コライ菌のNikRタンパク質は,
科学分野:
- バイオケミストリー バイオケミストリー
- 分子生物学は分子生物学である.
- 構造生物学 構造生物学とは
背景:
- PnikオペレオンによってコードされたE. coliのNi特異性浸透酵素は,NikRタンパク質によって調節されます.
- NikRの金属イオン特異性を理解することは,その規制メカニズムを明らかにするために不可欠です.
- 以前の研究では,ニッケル特異性トランスクリプション抑制を vivo で示した.
研究 の 目的:
- エシェリキヤ大腸のNikRタンパク質における金属イオン特異性の構造的基礎を調査する.
- 金属がNikRに結合することで,そのDNA結合活動に影響を与えるアロステリックメカニズムを解明する.
- 金属結合したNikR複合体の独特の構造的特徴を特徴づけること.
主な方法:
- X線吸収スペクトロスコーピー (XAS) を使用して,様々な金属-ニークR複合体 (Co ((II),Ni ((II),Cu ((II),Cu ((I),Zn ((II)) を分析した.
- 水素/デュテリウム (H/D) 交換質量スペクトロメトリ (LC-ESI-MS) を使用して,金属結合時のタンパク質構造の変化を評価しました.
- ヘテロビメタリック複合体は,XASを使用して,低親近性金属結合部位を特徴付けるために研究されました.
主要な成果:
- 高親和性金属がニークリオンに結合すると,独特のタンパク質構造が誘発され,Ni (II) とCu (II) が平面四座標複合体を形成する.
- NikRの金属特有の構造の変化は,H/D交換を通じて観察され,Ni (II) とCu (II) は,Apo-NikRと比較して異なる交換パターンを示した.
- 低親和性の金属結合部位を特徴付け,Ni (II) に対して6つのN/Oドナー環境と,Co (II) に対して同様の構造を明らかにし,後者の場合,塩化物をリガンドとして使用した.
結論:
- 高親和性金属イオンの幾何学とリガンド選択は,NikR適合とそれに続くDNA結合を決定し,アロステル調節モデルをサポートします.
- 異なる金属イオンに対するニッケルRの独特の構造反応は,ニッケル特有の機能を支えている.
- 高親和度および低親和度の両方の金属結合部位の特徴化は,NikRの金属検出機構の包括的な理解を提供します.
関連する概念動画
01:23Types of RNA
Overview
Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse functions and can be broadly classified as protein-coding or non-coding RNA. Non-coding RNAs play important roles in the regulation of gene expression in response to developmental and environmental changes. Non-coding RNAs in prokaryotes can be manipulated to develop more effective antibacterial drugs for human or animal use.
RNA...
Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse functions and can be broadly classified as protein-coding or non-coding RNA. Non-coding RNAs play important roles in the regulation of gene expression in response to developmental and environmental changes. Non-coding RNAs in prokaryotes can be manipulated to develop more effective antibacterial drugs for human or animal use.
RNA...
00:43Bacterial RNA Polymerase
Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
01:23Transcriptional Regulation: Riboswitches
Riboswitches are RNA elements that regulate gene expression by altering their secondary structures in response to specific effector molecules. These elements, located in the leader regions of certain mRNAs, act as transcriptional regulators by toggling between alternative conformations to control downstream gene expression. Riboswitch-mediated regulation is a precise mechanism for modulating biosynthetic pathways, as exemplified by the riboflavin biosynthesis pathway in Bacillus...
01:29Translational 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,...
01:28Global Regulatory Systems
Global regulatory systems in bacteria enable rapid and coordinated responses to environmental changes by integrating sensory inputs with gene expression, ensuring efficient adaptation to fluctuating conditions. Key global regulatory mechanisms include regulons, two-component systems, sigma factors, and secondary messengers.Regulons and Global RegulatorsA regulon is a collection of genes and operons controlled by a common global regulator. These regulators enable bacteria to prioritize resource...
01:23Stringent Response in E. coli
Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...