E. coliのカプスラーポリサッカリドのトランスロコンは,膜タンパク質の新しいクラスを定義しています
Changjiang Dong1, Konstantinos Beis, Jutta Nesper
1Centre for Biomolecular Sciences, The University of St Andrews, Fife KY16 9RH, UK.
Nature
|November 7, 2006
まとめ
研究者らは,Escherichia coliのバクテリアカプセルを輸出するのに不可欠なタンパク質であるWzaの構造を明らかにした. この発見は,細菌がどのようにして保護層を構築し,潜在的に他の大きな分子を輸出するかについての洞察を提供します.
科学分野:
- 微生物学 微生物学とは
- 構造生物学 構造生物学とは
- バイオケミストリー バイオケミストリー
背景:
- バクテリアは細胞外ポリサッカリド (EPS) を生成し,コロニゼーションと免疫逃避に役割を果たします.
- いくつかのEPSはカプセルを形成し,ホストの免疫システムからバクテリアを保護する層です.
- EPSには,産業および生物医学的な用途があります.
研究 の 目的:
- Escherichia coli.のグループ1カプセル輸出に不可欠なタンパク質であるWzaの構造を決定する.
- バクテリアの外膜を横断するカプスラーポリサッカリドの転位のメカニズムを解明する.
主な方法:
- X線結晶学を用いて,Wzaオクターマーの2.26A解像度構造を決定した.
- 構造分析は,Wza.のトランスメブラン領域とペリプラズマ領域に焦点を当てました.
主要な成果:
- Wzaの340 kDaオクタマーは解明され,新しいアルファ-ヘリコプターバレルトランスメブラン領域を明らかにしました.
- Wzaの周辺プラズマ部分には,大きな中央空洞を形成する3つの新しい領域が含まれています.
- Wzaの構造は細胞外環境に対して開かれているが,周辺プラズマに対して閉ざされており,特定の転位経路を示唆している.
結論:
- Wzaの構造は,Escherichia coli.のグループ1カプセル輸出のモデルを提供します.
- Wza.を介してカプセルポリサッカリドの転位のための提案されたメカニズム.
- 発見は,DNAやタンパク質などの他の大きな極性分子輸出システムについての理解を促す可能性がある.
関連する概念動画
Cotranslational Protein Translocation
Translocation of proteins across membranes is an ancient process that occurs even in bacteria and archaebacteria. In fact, the components of the translocation machinery are still conserved between prokaryotes and eukaryotes.
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Insertion of Single-pass Transmembrane Proteins in the RER
Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
Protein Translocation Machinery on the ER Membrane
The translocon complex situated on the ER membrane is the main gateway for the protein secretory pathway. It facilitates the transport of nascent peptides into the ER lumen and their insertion into the ER membrane.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the translocon complex.
Formation of Lipopolysaccharides
Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin, triggering...
Bacterial Translocation and Protein Secretion
Bacterial protein secretion involves translocation systems to ensure proteins reach their designated locations, including the plasma membrane, periplasm, outer membrane, or the external environment. These translocation systems are vital for bacterial physiology, supporting processes like membrane assembly, enzymatic activity in the periplasm, and interactions with the external environment. The division of labor between Sec and Tat pathways ensures efficiency in handling proteins with diverse...


