エウリアアケアのリシル-tRNA合成酵素:クラスI合成酵素に類似している
1Department of Molecular Biophysics and Biochemistry, Yale University, Post Office Box 208114, 266 Whitney Avenue, New Haven, CT 06520-8114, USA.
Science (New York, N.Y.)
|November 14, 1997
まとめ
メタノコックス・マリパルディス (Methanococcus maripaludis) で,新しいリジル転送RNA (tRNA) 合成酵素 (LysRS) が発見され,この必須酵素がEuryarchaea.で存在しないと推定されていることに異議を唱えた. このユニークなLysRSは,以前に知られているクラスII酵素とは異なり,クラスIに属しています.
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.
- アーカイアゲノミクス (Archaea Genomics) とは
背景:
- ユーリアキアのゲノムには,リシル転送RNA (tRNA) 合成酵素 (LysRS) の遺伝子が欠けている.
- LysRSは,生命のあらゆる領域におけるタンパク質合成に不可欠である.
- 以前の理解では,LysRSはEuryarchaeaに存在しないと示唆されていた.
研究 の 目的:
- ユリアケアにおけるライスRSの存在と性質を調査する.
- Methanococcus maripaludisで特定された新しいLysRSを特徴付けるために.
- 生命体におけるアミノアシル-tRNA合成酵素の分類を再評価する.
主な方法:
- Methanococcus maripaludis.からタンパク質を浄化する.
- 遺伝子クローニングとシーケンシング.
- アミノ酸配列分析とモチーフ識別.
- 酵素活性アッセイ. 酵素活性アッセイ.
主要な成果:
- カノニカルなLysRS活性を持つ62キロダルトンのタンパク質が,M. maripaludis.から浄化されました.
- M. maripaludisのLysRS遺伝子配列は,他のドメインの既知のLysRSタンパク質とは関係ありません.
- 配列解析により,LysRSはクラスIに属し,ロスマン・ジヌクレオチド結合モチーフによって特徴づけられていることが明らかになった.
- 同型の未指定の開いた読書フレームは,他のユーリアケアでも発見されました.
結論:
- Methanococcus maripaludisはユニークなクラスIのLysRSを有しており,Euryarchaea.でその推定不在に異議を唱える.
- この発見は,LysRSの分類と進化的理解の見直しを必要としている.
- この発見は,アミノアシル-tRNA合成酵素分類システムの普遍性に疑問を投げかけている.
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00:58Eukaryotic RNA Polymerases
RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...
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02:36Transfer RNA Synthesis
One of the unique features of tRNA is the presence of modified bases. In some tRNAs, modified bases account for nearly 20% of the total bases in the molecule. Altogether, these unusual bases protect the tRNA from enzymatic degradation by RNases.
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
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