1NSJ

CRYSTAL STRUCTURE OF PHOSPHORIBOSYL ANTHRANILATE ISOMERASE FROM THERMOTOGA MARITIMA

1NSJ の概要

• エントリーDOI: 10.2210/pdb1nsj/pdb
• 分子名称: PHOSPHORIBOSYL ANTHRANILATE ISOMERASE, PHOSPHATE ION (3 entities in total)
• 機能のキーワード: isomerase, phosphoribosyl anthranilate isomerase, thermostability
• 由来する生物種: Thermotoga maritima
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 23165.52

構造登録者

Hennig, M.,Jansonius, J.N.J. (登録日: 1996-09-13, 公開日: 1997-03-12, 最終更新日: 2024-02-14)

主引用文献

Hennig, M.,Sterner, R.,Kirschner, K.,Jansonius, J.N.
Crystal structure at 2.0 A resolution of phosphoribosyl anthranilate isomerase from the hyperthermophile Thermotoga maritima: possible determinants of protein stability.
Biochemistry, 36:6009-6016, 1997

PubMed Abstract: The structural basis of thermostability of proteins is of great scientific and biotechnological interest. Differences in the X-ray structues of orthologous proteins from hyperthermophilic and mesophilic organisms can indicate crucial stabilizing interactions. To this end the crystal structure of dimeric phosphoribosyl anthranilate isomerase from the hyperthermophile Thermotoga maritima (tPRAI) was determined using phases derived from the isomorphous replacement method and was refined at 2.0 A resolution. The comparison to the known 2.0 A structure of PRAI from Escherichia coli (ePRAI) shows that tPRAI has the complete TIM- or (beta alpha)8-barrel fold, whereas helix alpha5 in ePRAI is replaced by a loop. The subunits of tPRAI associate via the N-terminal faces of their central beta-barrels. Two long, symmetry-related loops that protrude reciprocally into cavities of the other subunit provide for multiple hydrophobic interactions. Moreover, the side chains of the N-terminal methionines and the C-terminal leucines of both subunits are immobilized in a hydrophobic cluster, and the number of salt bridges is increased in tPRAI. These features appear to be mainly responsible for the high thermostability of tPRAI. In contrast to other hyperthermostable enzymes, tPRAI at 25 degrees C is catalytically more efficient than ePRAI, mainly due to its small K(M) value for the substrate [Sterner, R., Kleemann, G. R., Szadkowski, H., Lustig, A., Hennig, M., & Kirschner, K. (1996) Protein Sci. 5, 2000-2008]. The increased number of hydrogen bonds between the phosphate ion and tPRAI compared to ePRAI could be responsible for this effect.

PubMed: 9166771
DOI: 10.1021/bi962718q

実験手法

X-RAY DIFFRACTION (2 Å)