2IO9

E. coli Bifunctional glutathionylspermidine synthetase/amidase Incomplex with Mg2+ ,GSH and ADP

Summary for 2IO9

• Entry DOI: 10.2210/pdb2io9/pdb
• Related: 2IO7 2IO8 2IOA 2IOB
• Descriptor: Bifunctional glutathionylspermidine synthetase/amidase, MAGNESIUM ION, ADENOSINE-5'-DIPHOSPHATE, ... (5 entities in total)
• Functional Keywords: bifunctional glutathionylspermidine synthetase/amidase, ligase, hydrolase
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 142789.74

Authors

Pai, C.H.,Chiang, B.Y.,Ko, T.P.,Chou, C.C.,Chong, C.M.,Yen, F.J.,Coward, J.K.,Wang, A.H.-J.,Lin, C.H. (deposition date: 2006-10-10, release date: 2006-12-12, Last modification date: 2011-07-13)

Primary citation

Pai, C.H.,Chiang, B.Y.,Ko, T.P.,Chou, C.C.,Chong, C.M.,Yen, F.J.,Chen, S.,Coward, J.K.,Wang, A.H.-J.,Lin, C.H.
Dual binding sites for translocation catalysis by Escherichia coli glutathionylspermidine synthetase
Embo J., 25:5970-5982, 2006

PubMed Abstract: Most organisms use glutathione to regulate intracellular thiol redox balance and protect against oxidative stress; protozoa, however, utilize trypanothione for this purpose. Trypanothione biosynthesis requires ATP-dependent conjugation of glutathione (GSH) to the two terminal amino groups of spermidine by glutathionylspermidine synthetase (GspS) and trypanothione synthetase (TryS), which are considered as drug targets. GspS catalyzes the penultimate step of the biosynthesis-amide bond formation between spermidine and the glycine carboxylate of GSH. We report herein five crystal structures of Escherichia coli GspS in complex with substrate, product or inhibitor. The C-terminal of GspS belongs to the ATP-grasp superfamily with a similar fold to the human glutathione synthetase. GSH is likely phosphorylated at one of two GSH-binding sites to form an acylphosphate intermediate that then translocates to the other site for subsequent nucleophilic addition of spermidine. We also identify essential amino acids involved in the catalysis. Our results constitute the first structural information on the biochemical features of parasite homologs (including TryS) that underlie their broad specificity for polyamines.

PubMed: 17124497
DOI: 10.1038/sj.emboj.7601440

Experimental method

X-RAY DIFFRACTION (2.2 Å)