3CSU

CATALYTIC TRIMER OF ESCHERICHIA COLI ASPARTATE TRANSCARBAMOYLASE

3CSU の概要

• エントリーDOI: 10.2210/pdb3csu/pdb
• 分子名称: PROTEIN (ASPARTATE CARBAMOYLTRANSFERASE), CALCIUM ION (3 entities in total)
• 機能のキーワード: transferase (carbamoyl-p, aspartate)
• 由来する生物種: Escherichia coli
• タンパク質・核酸の鎖数: 3
• 化学式量合計: 103091.47

構造登録者

Beernink, P.T.,Endrizzi, J.A.,Alber, T.,Schachman, H.K. (登録日: 1999-04-22, 公開日: 1999-05-11, 最終更新日: 2023-08-30)

主引用文献

Beernink, P.T.,Endrizzi, J.A.,Alber, T.,Schachman, H.K.
Assessment of the allosteric mechanism of aspartate transcarbamoylase based on the crystalline structure of the unregulated catalytic subunit.
Proc.Natl.Acad.Sci.USA, 96:5388-5393, 1999

PubMed Abstract: The lack of knowledge of the three-dimensional structure of the trimeric, catalytic (C) subunit of aspartate transcarbamoylase (ATCase) has impeded understanding of the allosteric regulation of this enzyme and left unresolved the mechanism by which the active, unregulated C trimers are inactivated on incorporation into the unliganded (taut or T state) holoenzyme. Surprisingly, the isolated C trimer, based on the 1.9-A crystal structure reported here, resembles more closely the trimers in the T state enzyme than in the holoenzyme:bisubstrate-analog complex, which has been considered as the active, relaxed (R) state enzyme. Unlike the C trimer in either the T state or bisubstrate-analog-bound holoenzyme, the isolated C trimer lacks 3-fold symmetry, and the active sites are partially disordered. The flexibility of the C trimer, contrasted to the highly constrained T state ATCase, suggests that regulation of the holoenzyme involves modulating the potential for conformational changes essential for catalysis. Large differences in structure between the active C trimer and the holoenzyme:bisubstrate-analog complex call into question the view that this complex represents the activated R state of ATCase.

PubMed: 10318893
DOI: 10.1073/pnas.96.10.5388

実験手法

X-RAY DIFFRACTION (1.88 Å)