Crystal Structures of Fumarate Hydratases from Leishmania major in a Complex with Inhibitor 2-Thiomalate

Leishmaniases affect the poorest people on earth and have no effective drug therapy. Here, we present the crystal structure of the mitochondrial isoform of class I fumarate hydratase (FH) from Leishmania major and compare it to the previously determined cytosolic Leishmania major isoform. We further describe the mechanism of action of the first class-specific FH inhibitor, 2-thiomalate, through X-ray crystallography and inhibition assays. Our crystal structures of both FH isoforms with inhibitor bound at 2.05 Å resolution and 1.60 Å resolution show high structural similarity. These structures further reveal that the selectivity of 2-thiomalate for class I FHs is due to direct coordination of the inhibitor to the unique Fe of the catalytic [4Fe-4S] cluster that is found in class I parasitic FHs but is absent from class II human FH. These studies provide the structural scaffold in order to exploit class I FHs as potential drug targets against leishmaniases as well as Chagas diseases, sleeping sickness, and malaria.Fundação de Amparo à Pesquisa do Estado de São Paulo (Grant 2013/14988-8)Fundação de Amparo à Pesquisa do Estado de São Paulo (Grant 2014/22246-4)Fundação de Amparo à Pesquisa do Estado de São Paulo (Grant 2008/08262-6)National Institute of General Medical Sciences (U.S.) (Grant R35 GM126982)National Institute of General Medical Sciences (U.S.) (Grant P41 GM103403)National Institutes of Health (U.S.). Office of Research Infrastructure Programs. High-End Instrumentation (HEI) Grant Program (Grant S10 RR029205)United States. Department of Energy. Office of Science (Contract DE-AC02-06CH11357