Crystal Structure of the 28 kDa Glutathione S-Transferase from Schistosoma haematobium
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- 作者：Kenneth A. Johnson ; Francesco Angelucci ; Andrea Bellelli ; Maxime Hervé ; Josette Fontaine ; Demetrious Tsernoglou ; André ; Capron ; Franç ; ois Trottein ; and Maurizio Brunori
- 刊名：Biochemistry
- 出版年：2003
- 出版时间：September 2, 2003
- 年：2003
- 卷：42
- 期：34
- 页码：10084 - 10094
- 全文大小：711K
- 年卷期：v.42,no.34(September 2, 2003)
- ISSN：1520-4995
文摘
Schistomiasis is a debilitating parasitic disease which affects 200 million people, causing life-threatening complications in 10% of the patients. This paper reports the crystal structure of the Schistosomahaematobium 28 kDa glutathione S-transferase, a multifunctional enzyme involved in host-parasiteinteractions and presently considered as a promising vaccine candidate against schistosomiasis. Thestructures of the GSH-free enzyme, as well as the partially (~40%) and almost fully (~80%) GSH-saturated enzyme, exhibit a unique feature, absent in previous GST structures, concerning the crucial andinvariant Tyr10 side chain which occupies two alternative positions. The canonical conformer, whichallows an H-bond to be formed between the side chain hydroxyl group and the activated thiolate of GSH,is somewhat less than 50% occupied. The new conformer, with the phenoxyl ring on the opposite side ofthe mobile loop connecting strand 1 and helix 1, is stabilized by a polar interaction with the guanidiniumgroup of the conserved Arg21 side chain. The presence of two conformers of Tyr10 may provide a clueabout clarifying the multiple catalytic functions of Sh28GST and might prove to be relevant for the designof specific antischistosomal drugs. The Kd for GSH binding was determined by equilibrium fluorescencetitrations to be ~3 
M and by stopped-flow rapid mixing experiments to be ~9 M. The relatively tightbinding of GSH by Sh28GST explains the residually bound GSH in the crystal and supports a possiblerole of GSH as a tightly bound cofactor involved in the catalytic mechanism for prostaglandin D2 synthaseactivity.
M and by stopped-flow rapid mixing experiments to be ~9 M. The relatively tightbinding of GSH by Sh28GST explains the residually bound GSH in the crystal and supports a possiblerole of GSH as a tightly bound cofactor involved in the catalytic mechanism for prostaglandin D2 synthaseactivity.