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Specificity of the trypanothione‐dependent Leishmania major glyoxalase I: structure and biochemical comparison with the human enzyme
Author(s) -
Ariza Antonio,
Vickers Tim J.,
Greig Neil,
Armour Kirsten A.,
Dixon Mark J.,
Eggleston Ian M.,
Fairlamb Alan H.,
Bond Charles S.
Publication year - 2006
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2006.05022.x
Subject(s) - methylglyoxal , lactoylglutathione lyase , glutathione , enzyme , biochemistry , biology , leishmania , antimonate , active site , cofactor , stereochemistry , chemistry , computer science , antimony , inorganic chemistry , parasite hosting , world wide web
Summary 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: N 1 ‐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 ( K i s of 0.54 µM and 12.6 µM, respectively), whereas S‐ 4‐bromobenzylglutathione is > 4000‐fold more active against human than L. major GLO1 ( K i s 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.