9EEO

Cryo-EM model of E. coli aspartate transcarbamoylase in the R-state complexed with CP, succinate, CTP, and Mg2+

9EEO の概要

• エントリーDOI: 10.2210/pdb9eeo/pdb
• 関連するPDBエントリー: 9EEH 9EEJ 9EEK 9EEL 9EEM 9EEN 9EEP 9EEQ 9EER 9EES 9EEU
• EMDBエントリー: 47956 47957 47958 47959 47960 47961 47963 47964 47965 47966
• 分子名称: Aspartate carbamoyltransferase, Aspartate carbamoyltransferase regulatory chain, PHOSPHORIC ACID MONO(FORMAMIDE)ESTER, ... (7 entities in total)
• 機能のキーワード: complex, allostery, atcase, r-state, cp, succinate, ctp, cytosolic protein
• 由来する生物種: Escherichia coli; 詳細
• タンパク質・核酸の鎖数: 12
• 化学式量合計: 316775.18

構造登録者

Patterson, M.G.,Miller, R.C.,Ando, N. (登録日: 2024-11-19, 公開日: 2026-04-15, 最終更新日: 2026-05-27)

主引用文献

Miller, R.C.,Patterson, M.G.,Bhatt, N.,Pei, X.,Ando, N.
Cooperativity in E. coli aspartate transcarbamoylase is tuned by allosteric breathing.
Nat Commun, 17:-, 2026

PubMed Abstract: Aspartate transcarbamoylase (ATCase) from Escherichia coli catalyzes a key step in pyrimidine nucleotide biosynthesis and has long served as a model for allosteric regulation. Despite decades of study, how nucleotide binding at distant regulatory sites controls cooperativity between active sites remained unresolved. Here we show that ATCase does not simply interconvert between two conformations, as traditionally depicted, but instead samples a continuum of conformations that tune enzyme cooperativity. Using complementary cryo-electron microscopy, small-angle X-ray scattering, and crystallography under conditions that ensure full assembly of the allosteric sites, we show that ATCase behaves like a flexible balloon whose global "breathing" motions directly regulate activity: compression enforces high cooperativity, inhibiting the enzyme, whereas expansion relieves this cooperativity and activates the enzyme. We further show that all four ribonucleoside triphosphates act in symmetric pairs to tune this motion, with the pyrimidines CTP and UTP compressing the enzyme to limit further pyrimidine production, and the purines ATP and GTP expanding it to balance pyrimidine and purine pools. Together, these findings uncover a dynamic breathing mechanism for long-range allosteric communication in ATCase.

PubMed: 41862478
DOI: 10.1038/s41467-026-70909-y

実験手法

ELECTRON MICROSCOPY (3.53 Å)