Leishmania amazonensis Arginase Compartmentalization in the Glycosome Is Important for Parasite Infectivity

Abstract

In Leishmania, de novo polyamine synthesis is initiated by the cleavage of L-arginine to urea and L-ornithine by the action of arginase (ARG, E.C. 3.5.3.1). Previous studies in L. major and L. mexicana showed that ARG is essential for in vitro growth in the absence of polyamines and needed for full infectivity in animal infections. The ARG protein is normally found within the parasite glycosome, and here we examined whether this localization is required for survival and infectivity. First, the localization of L. amazonensis ARG in the glycosome was confirmed in both the promastigote and amastigote stages. As in other species, arg− L. amazonensis required putrescine for growth and presented an attenuated infectivity. Restoration of a wild type ARG to the arg − mutant restored ARG expression, growth and infectivity. In contrast, restoration of a cytosol-targeted ARG lacking the glycosomal SKL targeting sequence (argΔSKL) restored growth but failed to restore infectivity. Further study showed that the ARGΔSKL protein was found in the cytosol as expected, but at very low levels. Our results indicate that the proper compartmentalization of L. amazonensis arginase in the glycosome is important for enzyme activity and optimal infectivity. Our conjecture is that parasite arginase participates in a complex equilibrium that defines the fate of L-arginine and that its proper subcellular location may be essential for this physiological orchestration.

Heme Uptake Mediated by LHR1 Is Essential for Leishmania amazonensis Virulence

“…4A). This was not unexpected, since a lack of robust complementation has been frequently observed in transgenic Leishmania (33)(34)(35). Nine weeks after infection, the mice were sacrificed, and footpad tissue was collected for parasite quantification by limiting dilution.…”

Antileishmanial activity of standardized fractions of Stryphnodendron obovatum (Barbatimão) extract and constituent compounds

“…Because the redox system plays an important role in parasite survival within the host, targeting this system represents a valid parasitekilling strategy (Tepe et al, 2011). Arginase (ARG), an enzyme in the PA pathway, also prevents oxidative stress in trypanosomatids, and is considered a therapeutic target to control Leishmania infection (Silva et al, 2012). Interestingly, C (4) is a competitive inhibitor, ECCG (5) is a mixed inhibitor, and GA (1) is a noncompetitive inhibitor of ARG (Reis et al, 2013).…”

Glycosome turnover inLeishmania majoris mediated by autophagy

“…23 Compartmentalization of metabolic pathways in this manner prevents the accumulation of toxic intermediates which would otherwise damage the cell, 24 and is also thought to facilitate rapid metabolic adaptation in response to changing environments. 23 Studies in both Leishmania and trypanosomes have shown that proper biogenesis of glycosomes and the correct targeting of glycosomal enzymes are essential for parasite survival, [24][25][26][27][28][29] making these unique organelles an attractive drug target. An increased association of glycosomal markers with the lysosome during the differentiation of Trypanosoma brucei, from the short-stumpy trypomastigote to the procyclic trypomastigote, has been reported and this was interpreted by the authors as microautophagy and thought to be important for adaptation of the parasite's metabolic machinery in readiness for the next life-cycle environment.…”