Higher expression of proline dehydrogenase altered mitochondrial function and increased Trypanosoma cruzi differentiation in vitro and in the insect vector

Abstract

The pathogenic protist Trypanosoma cruzi uses kissing bugs as intermediate hosts that vectorize the infection among mammals. This parasite oxidizes proline to glutamate through two enzymatic steps and one nonenzymatic step. In insect vectors, T. cruzi differentiates from a noninfective replicating form to nonproliferative infective forms. Proline sustains this differentiation, but to date, a link between proline metabolism and differentiation has not been established. In T. cruzi, the enzymatic steps of the proline-glutamate oxidation pathway are catalysed exclusively by the mitochondrial enzymes proline dehydrogenase [TcPRODH, EC: 1.5.5.2] and D1-pyrroline-5-carboxylate dehydrogenase [TcP5CDH, EC: 1.2.1.88]. Both enzymatic steps produce reducing equivalents that are able to directly feed the mitochondrial electron transport chain (ETC) and thus produce ATP. In this study, we demonstrate the contribution of each enzyme of the proline-glutamate pathway to ATP production. In addition, we show that parasites overexpressing these enzymes produce increased levels of H2O2, but only those overexpressing TcP5CDH produce increased levels of superoxide anion. We show that parasites overexpressing TcPRODH, but not parasites overexpressing TcP5CDH, exhibit a higher rate of differentiation into metacyclic trypomastigotes in vitro. Finally, insect hosts infected with parasites overexpressing TcPRODH showed a diminished parasitic load but a higher percent of metacyclic trypomastigotes, when compared with controls. Our data show that parasites overexpressing both, PRODH and P5CDH had increased mitochondrial functions that orchestrated different oxygen signalling, resulting in different outcomes in relation to the efficiency of parasitic differentiation in the invertebrate host.

Genetic and functional dissection of the glutamate-proline pathway reveals a shortcut for glutamate catabolism inLeishmania

“…Additionally, Glu will be catabolised into α-ketoglutarate and participate in the anaplerosis of the TCA cycle, further stimulating energy production (10,15,16,71,72).…”

“…Both FADH 2 and NADH can directly feed the mitochondrial electron transport chain and fuel ATP production. Additionally, Glu will be catabolised into α-ketoglutarate and participate in the anaplerosis of the TCA cycle, further stimulating energy production (10, 15, 16, 71, 72). Future biochemical characterisation of each one of the enzymes involved in Pro catabolism is necessary to answer if this hypothesis holds true.…”

Small molecule mediators of host-T. cruzi-environment interactions in Chagas disease

“…Conversely, the vector microbiome can synthesize all 8 group B vitamins and tetrahydrofolate, which may provide essential nutrients for T. cruzi given its auxotrophies (see below) [20,21]. T. cruzi is also an auxotroph for many amino acids [22] and can use amino acids as energy sources and inducers of parasite differentiation [23][24][25]. Actinomyces in the vector microbiome may be a source of histidine [26], and functional capabilities across amino acid metabolic pathways were found by metagenomic analysis of the R. prolixus gut microbiome [21].…”

Mitochondrial adaptations throughout the Trypanosoma brucei life cycle

“…These attributes correlated with a more efficient differentiation of the parasite to metacyclic trypomastigotes in vitro and within the insect vector. These outcomes provide a link between mitochondrial metabolism and efficient progression through trypanosoma development (Mantilla et al, 2021).…”