デカメリック SelA•tRNA(Sec) リング構造は,細菌のセレノシステイン形成のメカニズムを明らかにします
Yuzuru Itoh1, Markus J Bröcker, Shun-ichi Sekine
1RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan.
まとめ
バクテリアのセレノシステイン (Sec) 合成には,SelA酵素が関与し,機能に不可欠なリング構造を形成します. この研究は,SelaAを明らかにしています.
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:
- 21番目のアミノ酸であるセレノシステイン (Sec) は,翻訳後に合成されます.
- Sec合成には2つの異なる経路が存在します:細菌 (SelA) と古生物/真核生物 (SepSecS).
研究 の 目的:
- SelAによるバクテリアのSec合成の構造的基礎を解明する.
- SelA.によってtRNAの認識とSec形成のメカニズムを理解する.
主な方法:
- Aquifex aeolicus SelA複合体のX線結晶学について.
- インビヴォおよびインビトロ酵素アッセイ.
主要な成果:
- SelAの結晶構造を決定し,10個のtRNA (((Sec) 分子を結合する環状のホモデカメールを明らかにした.
- 特定のD-アーム結合とSer-tRNAの差別におけるN-端末ドメインの役割を特定した.
- 示されたデカメリゼーションは,SelaA活性とピリドクサルの5'-リン酸塩依存性Sec.形成に不可欠である.
結論:
- 細菌と古生物/真核生物のSec合成経路は,異なるタンパク質構造と基板の協調によって支えられ,独立して進化した.
- SelAのユニークな構造は,特定の基板結合と触媒を容易にし,進化の分岐を強調しています.
関連する概念動画
Septins
Septins are protein filaments forming the cytoskeleton along with the microtubules, microfilaments, intermediate filaments, and other accessory proteins. In 1971 while studying the cell division cycle in mutant Saccharomyces cerevisiae Harwell et al. first identified the septin-related genes playing a crucial role in yeast cytokinesis. Fluorescence microscopy revealed that these proteins localize at the budding neck as rings. These ring-like proteins were then named Septins by John Pringle, and...
Sulfur Assimilation
Sulfur is an essential element in biological systems, contributing to synthesizing key biomolecules, including amino acids such as cysteine and methionine, and cofactors such as coenzyme A and biotin. Microorganisms primarily assimilate sulfur as sulfate (SO₄²⁻) from the environment, which must undergo a series of biochemical transformations before it can be incorporated into cellular components. As sulfate is highly oxidized, it must undergo assimilatory sulfate reduction to become...
Protein Organization
Overview
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.
Protein Folding
Overview
Peptidoglycan Synthesis
Structure of PeptidoglycanPeptidoglycan is a vital structural component of the bacterial cell wall, providing mechanical strength and shape to the cell. It consists of repeating units of two sugars—N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)—linked by β-1,4 glycosidic bonds. These sugar chains are cross-linked by short peptide chains, forming a mesh-like polymer that surrounds the bacterial plasma membrane.Cytoplasmic Phase – Precursor SynthesisPeptidoglycan biosynthesis begins in...


