3TYP

The crystal structure of the inorganic triphosphatase NE1496

3TYP の概要

• エントリーDOI: 10.2210/pdb3typ/pdb
• 関連するPDBエントリー: 2FBL
• 分子名称: Uncharacterized protein, SODIUM ION, 1,2-ETHANEDIOL, ... (4 entities in total)
• 機能のキーワード: inorganic triphosphatase, hydrolase
• 由来する生物種: Nitrosomonas europaea
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 35736.17

構造登録者

Lunin, V.V.,Skarina, T.,Onopriyenko, O.,Binkowski, T.A.,Joachimiak, A.,Edwards, A.M.,Savchenko, A. (登録日: 2011-09-26, 公開日: 2012-05-09, 最終更新日: 2024-02-28)

主引用文献

Delvaux, D.,Murty, M.R.V.S.,Gabelica, V.,Lakaye, B.,Lunin, V.V.,Skarina, T.,Onopriyenko, O.,Kohn, G.,Wins, P.,De Pauw, E.,Bettendorff, L.
A specific inorganic triphosphatase from Nitrosomonas europaea: structure and catalytic mechanism.
J.Biol.Chem., 286:34023-34035, 2011

PubMed Abstract: The CYTH superfamily of proteins is named after its two founding members, the CyaB adenylyl cyclase from Aeromonas hydrophila and the human 25-kDa thiamine triphosphatase. Because these proteins often form a closed β-barrel, they are also referred to as triphosphate tunnel metalloenzymes (TTM). Functionally, they are characterized by their ability to bind triphosphorylated substrates and divalent metal ions. These proteins exist in most organisms and catalyze different reactions depending on their origin. Here we investigate structural and catalytic properties of the recombinant TTM protein from Nitrosomonas europaea (NeuTTM), a 19-kDa protein. Crystallographic data show that it crystallizes as a dimer and that, in contrast to other TTM proteins, it has an open β-barrel structure. We demonstrate that NeuTTM is a highly specific inorganic triphosphatase, hydrolyzing tripolyphosphate (PPP(i)) with high catalytic efficiency in the presence of Mg(2+). These data are supported by native mass spectrometry analysis showing that the enzyme binds PPP(i) (and Mg-PPP(i)) with high affinity (K(d) < 1.5 μm), whereas it has a low affinity for ATP or thiamine triphosphate. In contrast to Aeromonas and Yersinia CyaB proteins, NeuTTM has no adenylyl cyclase activity, but it shares several properties with other enzymes of the CYTH superfamily, e.g. heat stability, alkaline pH optimum, and inhibition by Ca(2+) and Zn(2+) ions. We suggest a catalytic mechanism involving a catalytic dyad formed by Lys-52 and Tyr-28. The present data provide the first characterization of a new type of phosphohydrolase (unrelated to pyrophosphatases or exopolyphosphatases), able to hydrolyze inorganic triphosphate with high specificity.

PubMed: 21840996

実験手法

X-RAY DIFFRACTION (1.9 Å)