2R91

Crystal Structure of KD(P)GA from T.tenax

2R91 の概要

• エントリーDOI: 10.2210/pdb2r91/pdb
• 関連するPDBエントリー: 2R94
• 分子名称: 2-Keto-3-deoxy-(6-phospho-)gluconate aldolase, SULFATE ION (3 entities in total)
• 機能のキーワード: tim barrel, aldolase, thermophilic, lyase
• 由来する生物種: Thermoproteus tenax
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 124453.63

構造登録者

Pauluhn, A.,Pohl, E.,Lorentzen, E.,Siebers, B.,Ahmed, H.,Buchinger, S.,Schomburg, D. (登録日: 2007-09-12, 公開日: 2008-03-18, 最終更新日: 2024-11-20)

主引用文献

Pauluhn, A.,Ahmed, H.,Lorentzen, E.,Buchinger, S.,Schomburg, D.,Siebers, B.,Pohl, E.
Crystal structure and stereochemical studies of KD(P)G aldolase from Thermoproteus tenax.
Proteins, 72:35-43, 2008

PubMed Abstract: Carbon-carbon bond forming enzymes offer great potential for organic biosynthesis. Hence there is an ongoing effort to improve their biocatalytic properties, regarding availability, activity, stability, and substrate specificity and selectivity. Aldolases belong to the class of C-C bond forming enzymes and play important roles in numerous cellular processes. In several hyperthermophilic Archaea the 2-keto-3-deoxy-(6-phospho)-gluconate (KD(P)G) aldolase was identified as a key player in the metabolic pathway. The carbohydrate metabolism of the hyperthermophilic Crenarchaeote Thermoproteus tenax, for example, has been found to employ a combination of a variant of the Embden-Meyerhof-Parnas pathway and an unusual branched Entner-Doudoroff pathway that harbors a nonphosphorylative and a semiphosphorylative branch. The KD(P)G aldolase catalyzes the reversible cleavage of 2-keto-3-deoxy-6-phosphogluconate (KDPG) and 2-keto-3-deoxygluconate (KDG) forming pyruvate and glyceraldehyde 3-phosphate or glyceraldehyde, respectively. In T. tenax initial studies revealed that the pathway is specific for glucose, whereas in the thermoacidophilic Crenarchaeote Sulfolobus solfataricus the pathway was shown to be promiscuous for glucose and galactose degradation. The KD(P)G aldolase of S. solfataricus lacks stereo control and displays additional activity with 2-keto-3-deoxy-6-phosphogalactonate (KDPGal) and 2-keto-3-deoxygalactonate (KDGal), similar to the KD(P)G aldolase of Sulfolobus acidocaldarius. To address the stereo control of the T. tenax enzyme the formation of the two C4 epimers KDG and KDGal was analyzed via gas chromatography combined with mass spectroscopy. Furthermore, the crystal structure of the apoprotein was determined to a resolution of 2.0 A, and the crystal structure of the protein covalently linked to a pathway intermediate, namely pyruvate, was determined to 2.2 A. Interestingly, although the pathway seems to be specific for glucose in T. tenax the enzyme apparently also lacks stereo control, suggesting that the enzyme is a trade-off between required catabolic flexibility needed for the conversion of phosphorylated and nonphosphorylated substrates and required stereo control of cellular/physiological enzymatic reactions.

PubMed: 18186475
DOI: 10.1002/prot.21890

実験手法

X-RAY DIFFRACTION (2 Å)