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Crystal structure of arginase from Leishmania mexicana and implications for the inhibition of polyamine biosynthesis in parasitic infections
Journal article   Peer reviewed

Crystal structure of arginase from Leishmania mexicana and implications for the inhibition of polyamine biosynthesis in parasitic infections

Edward L D’Antonio, Buddy Ullman, Sigrid C Roberts, Upasna Gaur Dixit, Mary E Wilson, Yang Hai and David W Christianson
Archives of biochemistry and biophysics, Vol.535(2), pp.163-176
07/15/2013
DOI: 10.1016/j.abb.2013.03.015
PMCID: PMC3683356
PMID: 23583962

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Abstract

•Crystal structures of LmARG and its complexes with inhibitors have been determined.•The inhibitor nor-NOHA attenuates parasite proliferation, albeit weakly.•LmARG structures will enable the design of selective inhibitors with improved parasite uptake properties. Arginase from parasitic protozoa belonging to the genus Leishmania is a potential drug target for the treatment of leishmaniasis because this binuclear manganese metalloenzyme catalyzes the first committed step in the biosynthesis of polyamines that enable cell growth and survival. The high resolution X-ray crystal structures of the unliganded form of Leishmania mexicana arginase (LmARG) and four inhibitor complexes are now reported. These complexes include the reactive substrate analogue 2(S)-amino-6-boronohexanoic acid (ABH) and the hydroxylated substrate analogue nor-Nω-hydroxy-l-arginine (nor-NOHA), which are the most potent arginase inhibitors known to date. Comparisons of the LmARG structure with that of the archetypal arginase, human arginase I, reveal that all residues important for substrate binding and catalysis are strictly conserved. However, three regions of tertiary structure differ between the parasitic enzyme and the human enzyme corresponding to the G62 – S71, L161 – C172, and I219 – V230 segments of LmARG. Additionally, variations are observed in salt link interactions that stabilize trimer assembly in LmARG. We also report biological studies in which we demonstrate that localization of LmARG to the glycosome, a unique subcellular organelle peculiar to Leishmania and related parasites, is essential for robust pathogenesis.
X-ray crystallography Arginase Leishmaniasis Metalloenzyme

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