4F8B

Crystal Structure of the Covalent Thioimide Intermediate of Unimodular Nitrile Reductase QueF

4F8B の概要

• エントリーDOI: 10.2210/pdb4f8b/pdb
• 関連するPDBエントリー: 4FGC
• 分子名称: NADPH-dependent 7-cyano-7-deazaguanine reductase, 2-amino-5-[(Z)-iminomethyl]-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one, MAGNESIUM ION, ... (6 entities in total)
• 機能のキーワード: beta barrel, protein thioimide complex, pterin binding fold, tunnel fold, trna modification enzyme, 7-cyano-7-deazaguanine, nadph, oxidoreductase
• 由来する生物種: Bacillus subtilis subsp. subtilis
• 細胞内の位置: Cytoplasm : O31678
• タンパク質・核酸の鎖数: 5
• 化学式量合計: 98240.05

構造登録者

Stec, B.,Swairjo, M.A. (登録日: 2012-05-17, 公開日: 2012-07-11, 最終更新日: 2024-11-06)

主引用文献

Chikwana, V.M.,Stec, B.,Lee, B.W.,de Crecy-Lagard, V.,Iwata-Reuyl, D.,Swairjo, M.A.
Structural basis of biological nitrile reduction.
J.Biol.Chem., 287:30560-30570, 2012

PubMed Abstract: The enzyme QueF catalyzes the reduction of the nitrile group of 7-cyano-7-deazaguanine (preQ(0)) to 7-aminomethyl-7-deazaguanine (preQ(1)), the only nitrile reduction reaction known in biology. We describe here two crystal structures of Bacillus subtilis QueF, one of the wild-type enzyme in complex with the substrate preQ(0), trapped as a covalent thioimide, a putative intermediate in the reaction, and the second of the C55A mutant in complex with the substrate preQ(0) bound noncovalently. The QueF enzyme forms an asymmetric tunnel-fold homodecamer of two head-to-head facing pentameric subunits, harboring 10 active sites at the intersubunit interfaces. In both structures, a preQ(0) molecule is bound at eight sites, and in the wild-type enzyme, it forms a thioimide covalent linkage to the catalytic residue Cys-55. Both structural and transient kinetic data show that preQ(0) binding, not thioimide formation, induces a large conformational change in and closure of the active site. Based on these data, we propose a mechanism for the activation of the Cys-55 nucleophile and subsequent hydride transfer.

PubMed: 22787148
DOI: 10.1074/jbc.M112.388538

実験手法

X-RAY DIFFRACTION (2.502 Å)