1NM5

R. rubrum transhydrogenase (dI.Q132N)2(dIII)1 asymmetric complex

1NM5 の概要

• エントリーDOI: 10.2210/pdb1nm5/pdb
• 関連するPDBエントリー: 1HZZ
• 分子名称: NAD(P) transhydrogenase subunit alpha part 1, NAD(P) transhydrogenase subunit beta, NICOTINAMIDE-ADENINE-DINUCLEOTIDE, ... (6 entities in total)
• 機能のキーワード: asymmetric complex, rossman domain, oxidoreductase
• 由来する生物種: Rhodospirillum rubrum; 詳細
• 細胞内の位置: Cell inner membrane; Multi-pass membrane protein (By similarity): Q59765
• タンパク質・核酸の鎖数: 3
• 化学式量合計: 104269.38

構造登録者

Van Boxel, G.I.,Quirk, P.G.,Cotton, N.P.,White, S.A.,Jackson, J.B. (登録日: 2003-01-09, 公開日: 2004-01-13, 最終更新日: 2023-08-16)

主引用文献

van Boxel, G.I.,Quirk, P.G.,Cotton, N.P.,White, S.A.,Jackson, J.B.
Glutamine 132 in the NAD(H)-binding component of proton-translocating transhydrogenase tethers the nucleotides before hydride transfer.
Biochemistry, 42:1217-1226, 2003

PubMed Abstract: Transhydrogenase, found in bacterial membranes and inner mitochondrial membranes of animal cells, couples the redox reaction between NAD(H) and NADP(H) to proton translocation. In this work, the invariant Gln132 in the NAD(H)-binding component (dI) of the Rhodospirillum rubrum transhydrogenase was substituted with Asn (to give dI.Q132N). Mixtures of the mutant protein and the NADP(H)-binding component (dIII) of the enzyme readily produced an asymmetric complex, (dI.Q132N)(2)dIII(1). The X-ray structure of the complex revealed specific changes in the interaction between bound nicotinamide nucleotides and the protein at the hydride transfer site. The first-order rate constant of the redox reaction between nucleotides bound to (dI.Q132N)(2)dIII(1) was <1% of that for the wild-type complex, and the deuterium isotope effect was significantly decreased. The nucleotide binding properties of the dI component in the complex were asymmetrically affected by the Gln-to-Asn mutation. In intact, membrane-bound transhydrogenase, the substitution completely abolished all catalytic activity. The results suggest that Gln132 in the wild-type enzyme behaves as a "tether" or a "tie" in the mutual positioning of the (dihydro)nicotinamide rings of NAD(H) and NADP(H) for hydride transfer during the conformational changes that are coupled to the translocation of protons across the membrane. This ensures that hydride transfer is properly gated and does not take place in the absence of proton translocation.

PubMed: 12564924
DOI: 10.1021/bi027032e

実験手法

X-RAY DIFFRACTION (2.4 Å)