3MPU

Crystal structure of the C47A/A241C disulfide-linked E. coli Aspartate Transcarbamoylase holoenzyme

3MPU の概要

• エントリーDOI: 10.2210/pdb3mpu/pdb
• 関連するPDBエントリー: 1AT1 1D09 1R0B 1ZA2 2A0F
• 分子名称: Aspartate carbamoyltransferase catalytic chain, Aspartate carbamoyltransferase regulatory chain, PHOSPHATE ION, ... (5 entities in total)
• 機能のキーワード: aspartate trancarbamoylase, disulfide bond, phosphate, catalysis, product release, ordered-sequential mechanism, transferase
• 由来する生物種: Escherichia coli; 詳細
• タンパク質・核酸の鎖数: 6
• 化学式量合計: 155208.24

構造登録者

Mendes, K.R.,Kantrowitz, E.R. (登録日: 2010-04-27, 公開日: 2010-07-21, 最終更新日: 2024-11-20)

主引用文献

Mendes, K.R.,Kantrowitz, E.R.
The Pathway of Product Release from the R State of Aspartate Transcarbamoylase.
J.Mol.Biol., 401:940-948, 2010

PubMed Abstract: The pathway of product release from the R state of aspartate transcarbamoylase (ATCase; EC 2.1.3.2, aspartate carbamoyltransferase) has been determined here by solving the crystal structure of Escherichia coli ATCase locked in the R quaternary structure by specific introduction of disulfide bonds. ATCase displays ordered substrate binding and product release, remaining in the R state until substrates are exhausted. The structure reported here represents ATCase in the R state bound to the final product molecule, phosphate. This structure has been difficult to obtain previously because the enzyme relaxes back to the T state after the substrates are exhausted. Hence, cocrystallizing the wild-type enzyme with phosphate results in a T-state structure. In this structure of the enzyme trapped in the R state with specific disulfide bonds, we observe two phosphate molecules per active site. The position of the first phosphate corresponds to the position of the phosphate of carbamoyl phosphate (CP) and the position of the phosphonate of N-phosphonacetyl-l-aspartate. However, the second, more weakly bound phosphate is bound in a positively charged pocket that is more accessible to the surface than the other phosphate. The second phosphate appears to be on the path that phosphate would have to take to exit the active site. Our results suggest that phosphate dissociation and CP binding can occur simultaneously and that the dissociation of phosphate may actually promote the binding of CP for more efficient catalysis.

PubMed: 20620149
DOI: 10.1016/j.jmb.2010.07.003

実験手法

X-RAY DIFFRACTION (2.855 Å)