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| Subject Categories: Microbiology & Pathogens | Structural Biology |
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| The EMBO Journal
(2006) 25, 5970–5982, doi:10.1038/sj.emboj.7601440 Published online 23 November 2006 |
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| Dual binding sites for translocation catalysis by Escherichia coli glutathionylspermidine synthetase |
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| Chien-Hua Pai1, 2, Bing-Yu Chiang1, 3, Tzu- Ping Ko1, Chia-Cheng Chou4, Cheong-Meng Chong1, Fang-Jiun Yen1, Shoujun Chen5, James K Coward3, Andrew H-J Wang1, 3, 4 and Chun-Hung Lin1, 3, 4 |
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1 Institute of Biological Chemistry, Academia Sinica, Nan-Kang, Taipei, Taiwan 2 Institute of Biochemistry, National Yang-Ming University, Taipei, Taiwan 3 Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan 4 Genomics Research Center, Academia Sinica, Taipei, Taiwan 5 Departments of Medicinal Chemistry & Chemistry, University of Michigan, Ann Arbor, MI, USA To whom correspondence should be addressed Andrew H-J Wang, Institute of Biological Chemistry, Academia Sinica, No. 128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan. Tel.: +886 2 2788 1981; Fax: +886 2 2788 2043; E-mail: ahjwang@gate.sinica.edu.tw Chun-Hung Lin, Institute of Biological Chemistry, Academia Sinica, No. 128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan. Tel.: +886 2 2789 0110; Fax: +886 2 4705; E-mail: chunhung@gate.sinica.edu.tw Received 3 July 2006; Accepted 12 October 2006; Published online 23 November 2006. |
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| Abstract |
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| 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. |
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| Keywords: binding site, glutathionylspermidine, mechanism, structure, trypanothione |
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Top of page MORE ARTICLES LIKE THISThese links to content published by NPG are automatically generated RESEARCHDual binding sites for translocation catalysis by Escherichia coli glutathionylspermidine synthetase The EMBO Journal Article Molecular basis of glutathione synthetase deficiency and a rare gene permutation event The EMBO Journal Article (15 Jun 1999) Comparative genomic analysis of three Leishmania species that cause diverse human disease Nature Genetics Article (01 Jul 2007) |
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