4RL4

Crystal structure of GTP cyclohydrolase II from Helicobacter pylori 26695

4RL4 の概要

• エントリーDOI: 10.2210/pdb4rl4/pdb
• 関連するPDBエントリー: 2BZ0 4I14
• 分子名称: GTP cyclohydrolase-2, PYROPHOSPHATE (3 entities in total)
• 機能のキーワード: alpha/beta fold, hydrolase, darp, riboflavin
• 由来する生物種: Helicobacter pylori
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 48558.91

構造登録者

Yadav, S.,Karthikeyan, S. (登録日: 2014-10-15, 公開日: 2015-08-26, 最終更新日: 2024-11-06)

主引用文献

Yadav, S.,Karthikeyan, S.
Structural and biochemical characterization of GTP cyclohydrolase II from Helicobacter pylori reveals its redox dependent catalytic activity.
J.Struct.Biol., 192:100-115, 2015

PubMed Abstract: GTP cyclohydrolase II (GCHII), catalyzes the conversion of GTP to 2,5-diamino-6-β-ribosyl-4(3H)-pyrimidinone-5'-phosphate and has been shown to be essential for pathogens. Here we describe the biochemical, kinetic and structural characterization of GCHII from Helicobacter pylori (hGCHII). The crystal structure of hGCHII, unlike other GCHII structures, revealed that cysteines at the active site existed in oxidized state forming two disulfide bonds and lacked Zn(2+) that was shown to be indispensable for catalytic activity in other species. However, incubation of hGCHII with hydrogen peroxide, an oxidizing agent, followed by PAR-assay showed that Zn(2+) was intrinsically present, indicating that all cysteines at the catalytic site remained in reduced state. Moreover, site directed mutagenesis of catalytic site cysteines revealed that only three, out of four cysteines were essential for hGCHII activity. These results, though, indicated that hGCHII crystallized in oxidized form, the expulsion of Zn(2+) upon oxidation of catalytic cysteines revealed its ability to act in response to the redox environment. Exploring further, incubation of hGCHII with reversible thiol modifying agent S-methyl-methane-thiosulfonate resulted in loss of GCHII activity due to oxidation of its cysteine residues as revealed by mass spectrometry studies. However, addition of reducing agent DTT partially restored the hGCHII catalytic activity. Taken together, these results demonstrate that hGCHII can regulate its catalytic activity depending on the redox environment, a function hitherto unknown for GCHII.

PubMed: 26272484
DOI: 10.1016/j.jsb.2015.08.004

実験手法

X-RAY DIFFRACTION (2.199 Å)