9D65

Nitrile hydratase BR52A mutant

9D65 の概要

• エントリーDOI: 10.2210/pdb9d65/pdb
• 分子名称: Cobalt-containing nitrile hydratase subunit alpha, Cobalt-containing nitrile hydratase subunit beta (3 entities in total)
• 機能のキーワード: nitrile hydratase, lyase
• 由来する生物種: Pseudonocardia thermophila; 詳細
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 49271.62

構造登録者

Miller, C.G.,Holz, R.C.,Liu, D.,Kaley, N. (登録日: 2024-08-14, 公開日: 2024-08-28, 最終更新日: 2024-10-23)

主引用文献

Miller, C.,Huntoon, D.,Kaley, N.,Ogutu, I.,Fiedler, A.T.,Bennett, B.,Liu, D.,Holz, R.
Role of second-sphere arginine residues in metal binding and metallocentre assembly in nitrile hydratases.
J Inorg Biochem, 256:112565-, 2024

PubMed Abstract: Two conserved second-sphere βArg (R) residues in nitrile hydratases (NHase), that form hydrogen bonds with the catalytically essential sulfenic and sulfinic acid ligands, were mutated to Lys and Ala residues in the Co-type NHase from Pseudonocardia thermophila JCM 3095 (PtNHase) and the Fe-type NHase from Rhodococcus equi TG328-2 (ReNHase). Only five of the eight mutants (PtNHase βR52A, βR52K, βR157A, βR157K and ReNHase βR61A) were successfully expressed and purified. Apart from the PtNHase βR52A mutant that exhibited no detectable activity, the k values obtained for the PtNHase and ReNHase βR mutant enzymes were between 1.8 and 12.4 s amounting to <1% of the k values observed for WT enzymes. The metal content of each mutant was also significantly decreased with occupancies ranging from ∼10 to ∼40%. UV-Vis spectra coupled with EPR data obtained on the ReNHase mutant enzyme, suggest a decrease in the Lewis acidity of the active site metal ion. X-ray crystal structures of the four PtNHase βR mutant enzymes confirmed the mutation and the low active site metal content, while also providing insight into the active site hydrogen bonding network. Finally, DFT calculations suggest that the equatorial sulfenic acid ligand, which has been shown to be the catalytic nucleophile, is protonated in the mutant enzyme. Taken together, these data confirm the necessity of the conserved second-sphere βR residues in the proposed subunit swapping process and post-translational modification of the α-subunit in the α activator complex, along with stabilizing the catalytic sulfenic acid in its anionic form.

PubMed: 38677005
DOI: 10.1016/j.jinorgbio.2024.112565

実験手法

X-RAY DIFFRACTION (1.45 Å)