2つの触媒部位を持つ酵素構造で,基板のダブルシート選択を行う

O Nureki¹, D G Vassylyev, M Tateno

¹Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan.

Science (New York, N.Y.)

|May 9, 1998

まとめ

酵素による編集は,正確な遺伝情報の転送を保証します. イソルエキュル-tRNA合成酵素は,二重シートメカニズムを使用して,誤ったアミノ酸結合を選択的に水解し,翻訳の精度を維持します.

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:

遺伝情報の正確な転送は,タンパク質合成に不可欠です.
酵素編集メカニズムは,翻訳の忠誠性を維持する上で重要な役割を果たします.
イソルエキュル転送RNA合成酵素 (IleRS) は,編集活性を持つことが知られている.

研究の目的:

イソユキル転送RNA合成酵素における編集活動の構造的基礎を解明する.
酵素とその基質との複合体で高解像度の結晶構造を提供する.

主な方法:

酵素の構造を決定するために,X線結晶学を用いた.
結晶構造は2.5アングストームの解像度で解像しました.
L-イソレウシンとL-バリンを含む酵素複合体を分析した.

主要な成果:

結晶構造は,基板選択のための"ダブルシート"メカニズムを明らかにします.
最初のは,アミノ酸化領域 (ロスマン折り) に位置しています.
2つ目のエディティング・シーブは,固有の球状ベータ・バレル・ドメインに位置しています.

結論:

IleRSの二重ドメイン構造は,2段階の基板選択プロセスを促進します.
この構造的メカニズムは,酵素が相性アミノ酸と非相性アミノ酸を区別する能力を説明する.
この発見は,翻訳中に高精度遺伝情報転送を維持するための洞察を提供します.

さらに関連する動画

08:25

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks (MOFs)

Published on: January 17, 2020

14:37

Modeling an Enzyme Active Site using Molecular Visualization Freeware

Published on: December 25, 2021

関連する概念動画

02:34

Enzymes

Inside living organisms, enzymes act as catalysts for many biochemical reactions involved in cellular metabolism. The role of enzymes is to reduce the activation energies of biochemical reactions by forming complexes with its substrates. The lowering of activation energies favor an increase in the rates of biochemical reactions.
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...

00:49

Ligand Binding and Linkage

Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked. In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence the...

01:07

Catalytically Perfect Enzymes

The theory of catalytically perfect enzymes was first proposed by W.J. Albery and J. R. Knowles in 1976. These enzymes catalyze biochemical reactions at high-speed. Their catalytic efficiency values range from 108-109 M-1s-1. These enzymes are also called 'diffusion-controlled' as the only rate-limiting step in the catalysis is that of the substrate diffusion into the active site. Examples include triose phosphate isomerase, fumarase, and superoxide dismutase.

01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...

01:19

Allosteric Proteins-ATCase

Binding sites linkages can regulate a protein's function. For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...