3TIM

THE CRYSTAL STRUCTURE OF THE "OPEN" AND THE "CLOSED" CONFORMATION OF THE FLEXIBLE LOOP OF TRYPANOSOMAL TRIOSEPHOSPHATE ISOMERASE

3TIM の概要

• エントリーDOI: 10.2210/pdb3tim/pdb
• 分子名称: TRIOSEPHOSPHATE ISOMERASE (2 entities in total)
• 機能のキーワード: isomerase(intramolecular oxidoreductase)
• 由来する生物種: Trypanosoma brucei brucei
• 細胞内の位置: Glycosome: P04789
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 53903.89

構造登録者

Wierenga, R.K. (登録日: 1990-05-15, 公開日: 1991-10-15, 最終更新日: 2024-02-28)

主引用文献

Wierenga, R.K.,Noble, M.E.,Postma, J.P.,Groendijk, H.,Kalk, K.H.,Hol, W.G.,Opperdoes, F.R.
The crystal structure of the "open" and the "closed" conformation of the flexible loop of trypanosomal triosephosphate isomerase.
Proteins, 10:33-49, 1991

PubMed Abstract: Triosephosphate isomerase has an important loop near the active site which can exist in a "closed" and in an "open" conformation. Here we describe the structural properties of this "flexible" loop observed in two different structures of trypanosomal triosephosphate isomerase. Trypanosomal triosephosphate isomerase, crystallized in the presence of 2.4 M ammonium sulfate, packs as an asymmetric dimer of 54,000 Da in the crystallographic asymmetric unit. Due to different crystal contacts, peptide 167-180 (the flexible loop of subunit-1) is an open conformation, whereas in subunit-2, this peptide (residues 467-480) is in a closed conformation. In the closed conformation, a hydrogen bond exists between the tip of the loop and a well-defined sulfate ion which is bound to the active site of subunit-2. Such an active site sulfate is not present in subunit-1 due to crystal contacts. When the native (2.4 M ammonium sulfate) crystals are transferred to a sulfate-free mother liquor, the flexible loop of subunit-2 adopts the open conformation. From a closed starting model, this open conformation was discovered through molecular dynamics refinement without manual intervention, despite involving C alpha shifts of up to 7 A. The tip of the loop, residues 472, 473, 474, and 475, moves as a rigid body. Our analysis shows that in this crystal form the flexible loop of subunit-2 faces a solvent channel. Therefore the open and the closed conformations of this flexible loop are virtually unaffected by crystal contacts. The actual observed conformation depends only on the absence or presence of a suitable ligand in the active site.

PubMed: 2062827
DOI: 10.1002/prot.340100105

実験手法

X-RAY DIFFRACTION (2.8 Å)