The first two authors contributed equally to this work.
Specificity of the trypanothione-dependent Leishmania major glyoxalase I: structure and biochemical comparison with the human enzyme
Article first published online: 9 JAN 2006
Volume 59, Issue 4, pages 1239–1248, February 2006
How to Cite
Ariza, A., Vickers, T. J., Greig, N., Armour, K. A., Dixon, M. J., Eggleston, I. M., Fairlamb, A. H. and Bond, C. S. (2006), Specificity of the trypanothione-dependent Leishmania major glyoxalase I: structure and biochemical comparison with the human enzyme. Molecular Microbiology, 59: 1239–1248. doi: 10.1111/j.1365-2958.2006.05022.x
- Issue published online: 9 JAN 2006
- Article first published online: 9 JAN 2006
- Accepted 30 November, 2005.
Trypanothione replaces glutathione in defence against cellular damage caused by oxidants, xenobiotics and methylglyoxal in the trypanosomatid parasites, which cause trypanosomiasis and leishmaniasis. In Leishmania major, the first step in methylglyoxal detoxification is performed by a trypanothione-dependent glyoxalase I (GLO1) containing a nickel cofactor; all other characterized eukaryotic glyoxalases use zinc. In kinetic studies L. major and human enzymes were active with methylglyoxal derivatives of several thiols, but showed opposite substrate selectivities: N1-glutathionylspermidine hemithioacetal is 40-fold better with L. major GLO1, whereas glutathione hemithioacetal is 300-fold better with human GLO1. Similarly, S-4-bromobenzylglutathionylspermidine is a 24-fold more potent linear competitive inhibitor of L. major than human GLO1 (Kis of 0.54 µM and 12.6 µM, respectively), whereas S-4-bromobenzylglutathione is > 4000-fold more active against human than L. major GLO1 (Kis of 0.13 µM and > 500 µM respectively). The crystal structure of L. major GLO1 reveals differences in active site architecture to both human GLO1 and the nickel-dependent Escherichia coli GLO1, including increased negative charge and hydrophobic character and truncation of a loop that may regulate catalysis in the human enzyme. These differences correlate with the differential binding of glutathione and trypanothione-based substrates, and thus offer a route to the rational design of L. major-specific GLO1 inhibitors.