4P3X

Structure of the Fe4S4 quinolinate synthase NadA from Thermotoga maritima

4P3X の概要

• エントリーDOI: 10.2210/pdb4p3x/pdb
• 関連するPDBエントリー: 1WZU 4HHE
• 分子名称: Quinolinate synthase A, IRON/SULFUR CLUSTER, ZINC ION, ... (5 entities in total)
• 機能のキーワード: holo-protein, nad biosynthesis, catalytic triad, iron sulfur cluster, transferase
• 由来する生物種: Thermotoga maritima
• 細胞内の位置: Cytoplasm : Q9X1X7
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 35309.99

構造登録者

Cherrier, M.V.,Chan, A.,Darnault, C.,Reichmann, D.,Amara, P.,Ollagnier de Choudens, S.,Fontecilla-Camps, J.C. (登録日: 2014-03-10, 公開日: 2014-04-02, 最終更新日: 2023-09-27)

主引用文献

Cherrier, M.V.,Chan, A.,Darnault, C.,Reichmann, D.,Amara, P.,Ollagnier de Choudens, S.,Fontecilla-Camps, J.C.
The crystal structure of Fe4S4 quinolinate synthase unravels an enzymatic dehydration mechanism that uses tyrosine and a hydrolase-type triad.
J.Am.Chem.Soc., 136:5253-5256, 2014

PubMed Abstract: Quinolinate synthase (NadA) is a Fe4S4 cluster-containing dehydrating enzyme involved in the synthesis of quinolinic acid (QA), the universal precursor of the essential nicotinamide adenine dinucleotide (NAD) coenzyme. A previously determined apo NadA crystal structure revealed the binding of one substrate analog, providing partial mechanistic information. Here, we report on the holo X-ray structure of NadA. The presence of the Fe4S4 cluster generates an internal tunnel and a cavity in which we have docked the last precursor to be dehydrated to form QA. We find that the only suitably placed residue to initiate this process is the conserved Tyr21. Furthermore, Tyr21 is close to a conserved Thr-His-Glu triad reminiscent of those found in proteases and other hydrolases. Our mutagenesis data show that all of these residues are essential for activity and strongly suggest that Tyr21 deprotonation, to form the reactive nucleophilic phenoxide anion, is mediated by the triad. NadA displays a dehydration mechanism significantly different from the one found in archetypical dehydratases such as aconitase, which use a serine residue deprotonated by an oxyanion hole. The X-ray structure of NadA will help us unveil its catalytic mechanism, the last step in the understanding of NAD biosynthesis.

PubMed: 24650327
DOI: 10.1021/ja501431b

実験手法

X-RAY DIFFRACTION (1.65 Å)