2DET

Cocrystal structure of an RNA sulfuration enzyme MnmA and tRNA-Glu in the pre-reaction state

2DET の概要

• エントリーDOI: 10.2210/pdb2det/pdb
• 関連するPDBエントリー: 2DER 2DEU
• 分子名称: tRNA, tRNA-specific 2-thiouridylase mnmA, SULFATE ION (3 entities in total)
• 機能のキーワード: protein-rna complex, transferase-rna complex, transferase/rna
• 由来する生物種: Escherichia coli; 詳細
• 細胞内の位置: Cytoplasm: P25745
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 66886.39

構造登録者

Numata, T.,Ikeuchi, Y.,Fukai, S.,Suzuki, T.,Nureki, O. (登録日: 2006-02-17, 公開日: 2006-08-15, 最終更新日: 2024-11-13)

主引用文献

Numata, T.,Ikeuchi, Y.,Fukai, S.,Suzuki, T.,Nureki, O.
Snapshots of tRNA sulphuration via an adenylated intermediate
Nature, 442:419-424, 2006

PubMed Abstract: Uridine at the first anticodon position (U34) of glutamate, lysine and glutamine transfer RNAs is universally modified by thiouridylase into 2-thiouridine (s2U34), which is crucial for precise translation by restricting codon-anticodon wobble during protein synthesis on the ribosome. However, it remains unclear how the enzyme incorporates reactive sulphur into the correct position of the uridine base. Here we present the crystal structures of the MnmA thiouridylase-tRNA complex in three discrete forms, which provide snapshots of the sequential chemical reactions during RNA sulphuration. On enzyme activation, an alpha-helix overhanging the active site is restructured into an idiosyncratic beta-hairpin-containing loop, which packs the flipped-out U34 deeply into the catalytic pocket and triggers the activation of the catalytic cysteine residues. The adenylated RNA intermediate is trapped. Thus, the active closed-conformation of the complex ensures accurate sulphur incorporation into the activated uridine carbon by forming a catalytic chamber to prevent solvent from accessing the catalytic site. The structures of the complex with glutamate tRNA further reveal how MnmA specifically recognizes its three different tRNA substrates. These findings provide the structural basis for a general mechanism whereby an enzyme incorporates a reactive atom at a precise position in a biological molecule.

PubMed: 16871210
DOI: 10.1038/nature04896

実験手法

X-RAY DIFFRACTION (3.4 Å)