1DJO

Crystal structure of Pseudomonas 7A Glutaminase-asparaginase with the inhibitor donv covalently bound in the active site

1DJO の概要

• エントリーDOI: 10.2210/pdb1djo/pdb
• 関連するPDBエントリー: 1DJP 4PGA
• 分子名称: GLUTAMINASE-ASPARAGINASE, 4,4-dihydroxy-5-oxo-L-norvaline (2 entities in total)
• 機能のキーワード: pga, glutaminase, asparaginase, donv, 5-diazo-4-oxo-l-norvaline, glutaminase-asparaginase, suicide inhibitor, covalently bound inhibitor, hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• 由来する生物種: Pseudomonas sp.
• 細胞内の位置: Periplasm: P10182
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 71118.30

構造登録者

Ortlund, E.,Lacount, M.W.,Lewinski, K.,Lebioda, L. (登録日: 1999-12-03, 公開日: 2000-01-24, 最終更新日: 2025-03-19)

主引用文献

Ortlund, E.,Lacount, M.W.,Lewinski, K.,Lebioda, L.
Reactions of Pseudomonas 7A glutaminase-asparaginase with diazo analogues of glutamine and asparagine result in unexpected covalent inhibitions and suggests an unusual catalytic triad Thr-Tyr-Glu.
Biochemistry, 39:1199-1204, 2000

PubMed Abstract: Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of D and L isomers of glutamine and asparagine. Crystals of PGA were reacted with diazo analogues of glutamine (6-diazo-5-oxo-L-norleucine, DON) and asparagine (5-diazo-4-oxo-L-norvaline, DONV), which are known inhibitors of the enzyme. The derivatized crystals remained isomorphous to native PGA crystals. Their structures were refined to crystallographic R = 0.20 and R(free) = 0.24 for PGA-DON and R = 0.19 and R = 0.23 for PGA-DONV. Difference Fourier electron density maps clearly showed that both DON and DONV inactivate PGA through covalent inhibition. Continuous electron density connecting the inhibitor to both Thr20 and Tyr34 of the flexible loop was observed providing strong evidence that Thr20 is the primary catalytic nucleophile and that Tyr34 plays an important role in catalysis as well. The unexpected covalent binding observed in the PGA-DON and PGA-DONV complexes shows that a secondary reaction involving the formation of a Tyr34-inhibitor bond takes place with concomitant inactivation of PGA. The predicted covalent linkage is not seen, however, suggesting an alternative method of inhibition not yet seen for these diazo analogues. These surprising results give insight as to the role of the flexible loop Thr and Tyr in the catalytic mechanism.

PubMed: 10684596
DOI: 10.1021/bi991797d

実験手法

X-RAY DIFFRACTION (2 Å)