サーファクチン合成酵素の外部チオエステラーゼの選択性の構造的基礎
Alexander Koglin1, Frank Löhr, Frank Bernhard
1Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance and Cluster of Excellence Macromolecular Complexes (CEF), J.W.-Goethe University, 60438 Frankfurt am Main, Germany.
Nature
|August 16, 2008
まとめ
II型チオエステラーゼ (TEII) は,非リボソームペプチドおよびポリケチド合成酵素の重要な修復酵素である. 構造分析により,TEII酵素がどのように機能的なコファクターを再生し,タイプIチオエステラゼ (TEI) と区別するかを明らかにした.
科学分野:
- バイオケミストリー バイオケミストリー
- 構造生物学 構造生物学とは
- 分子生物学は分子生物学である.
背景:
- 非リボソームペプチド合成酵素 (NRPS) とポリケチド合成酵素 (PKS) は,様々な生物体における生物活性化合物の生成に不可欠である.
- これらのシステムは,製品放出のためのタイプI型チオエステラゼ (TEI) と,コファクター修復のためのタイプII型チオエステラゼ (TEII) を利用します.
- TEII酵素は,チオレーション (T) ドメインの4'-フォスフォパンテイン (4'-PP) コファクターを再生し,生物合成経路の中断を防止するために重要である.
研究 の 目的:
- バチルス・サブティリスから得られた第2型チオエステラーゼ (TEII) の3次元構造を解明する.
- TEIIとTEI酵素間の基質選択性とドメイン相互作用の構造的基礎を比較する.
- その基板との関係でTEIIの構成動態を調査する.
主な方法:
- X線結晶学により,Bacillus subtilis TEIIの構造を自由状態とTドメインの複合体の両方で決定しました.
- TEIIと既知のTEI構造を比較した構造分析が行われました.
- TEII酵素構成と基板相互作用を研究するために生化学的測定法を使用した.
主要な成果:
- この研究では,細菌のTEII酵素の高解像度3次元構造と,Tドメインを持つその複合体について報告しています.
- 構造的な比較は,TEIIとTEI酵素間の基質選択性とTドメイン相互作用の異なるメカニズムを強調しています.
- TEIIが複数の構成形態で存在し,基板結合により特定の構成形態の選択が誘発されることが実証されました.
結論:
- 構造的な洞察は,NRPSとPKS経路内のコファクター再生におけるTEII機能の分子理解を提供します.
- この発見は,二次代謝産物生物合成の理解に不可欠なTEIとTEII酵素の違いを明らかにしています.
- 形状選択メカニズムは,TEIIと基板の相互作用の特異性を強調し,これらの複雑な生物合成機構の完全性を維持するために不可欠です.
関連する概念動画
Surface Active Agents
Surfactants, named for their behavior at interfaces, positively adsorb at the interfaces of two phases, reducing interfacial tension. Their versatility as emulsifiers, detergents, and foaming agents stems from this ability. Surfactants, often termed amphiphiles, share the property of amphipathy, with molecules having both hydrophilic and hydrophobic portions. The hydrophilic part is called the head, and the hydrophobic part, including an elongated alkyl substituent, forms the tail.Surfactants...
Tail-anchoring of Proteins in the ER Membrane
Tail-anchored, or TA, proteins are estimated to make up to 3-5% of membrane proteins found in the eukaryotic cell. Such proteins have a single transmembrane domain located approximately 30 amino acid residues upstream from the C-terminal end. As a result, the signal recognition particle (SRP) cannot guide a TA protein to the ER membrane for cotranslational insertion. Hence, they are integrated into the ER membrane post-translationally using their C-terminal end as the anchor. TA proteins...
Preparation and Reactions of Thiols
Thiols are prepared using the hydrosulfide anion as a nucleophile in a nucleophilic substitution reaction with alkyl halides. For instance, bromobutane reacts with sodium hydrosulfide to give butanethiol.
Induced-fit Model
Most chemical reactions in cells require enzymes—biological catalysts that speed up the reaction without being consumed or permanently changed. They reduce the activation energy needed to convert the reactants into products. Enzymes are proteins, that usually work by binding to a substrate—a reactant molecule that they act upon.
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...
Preparation and Reactions of Sulfides
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
tRNA Activation
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...


