9E33

Polaromonas naphthalenivorans phosphoenolpyruvate carboxykinase in complex with PEP (C2221)

9E33 の概要

• エントリーDOI: 10.2210/pdb9e33/pdb
• 分子名称: Phosphoenolpyruvate carboxykinase [GTP], MANGANESE (II) ION, PHOSPHOENOLPYRUVATE, ... (4 entities in total)
• 機能のキーワード: inhibitor complex, metabolic enzyme, multi-temperature, ambient temperature, lyase
• 由来する生物種: Polaromonas naphthalenivorans
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 68576.30

構造登録者

McLeod, M.J.,Barwell, S.A.E.,Holyoak, T. (登録日: 2024-10-23, 公開日: 2025-10-29)

主引用文献

McLeod, M.J.,Yazdani, S.,Barwell, S.A.E.,Holyoak, T.
Structural mechanisms for cold-adapted activity of phosphoenolpyruvate carboxykinase.
Protein Sci., 34:e70326-e70326, 2025

PubMed Abstract: Temperature is a critical factor in enzyme function, as most enzymes are thermally activated. Across Earth's diverse environments (-20 to 120°C), enzymes have evolved to function optimally at their organism's growth temperature. Thermophilic enzymes must resist denaturation, while psychrophilic enzymes must maintain activity with limited thermal energy. Although principles underlying thermostability are well established, the mechanisms governing kinetic adaptation to temperature remain less understood. To investigate this, we characterized the kinetics and determined a comprehensive series of X-ray crystal structures of a psychrophilic, GTP-dependent phosphoenolpyruvate carboxykinase (PEPCK) bound to substrates and non-reactive mimics of the reaction coordinate. These structures were compared to those of a mesophilic PEPCK. PEPCK is a dynamic enzyme requiring substantial conformational changes during catalysis, particularly ordering of the active site Ω-loop lid. The psychrophilic enzyme exhibited a reduced catalytic efficiency (k/K) and lower optimal temperature (T) relative to its mesophilic counterpart. Structural comparisons revealed substitutions in the Ω-loop that likely increase the entropic cost of loop ordering and reduce enthalpic stabilization, hindering efficient active site closure. These results provide a mechanistic basis for cold adaptation in enzyme catalysis, linking specific structural features to altered kinetic behavior. Understanding such adaptations not only advances our knowledge of enzyme evolution but also informs protein engineering efforts aimed at designing efficient biocatalysts for industrial applications operating at non-physiological temperatures.

PubMed: 41099612
DOI: 10.1002/pro.70326

実験手法

X-RAY DIFFRACTION (1.74 Å)