Trypanosoma cruziamino acid transporter TcAAAP411 mediates arginine uptake in yeasts

Abstract

Trypanosoma cruzi, the aetiological agent of Chagas' disease, is exposed to extremely different environment conditions during its life cycle, and transporters are key molecules for its adaptive regulation. Amino acids, and particularly arginine, are essential components in T. cruzi metabolism. In this work, a novel T. cruzi arginine permease was identified by screening different members of the AAAP family (amino acid/auxin permeases) in yeast complementation assays using a toxic arginine analogue. One gene candidate, TcAAAP411, was characterized as a very specific, high-affinity, l-arginine permease. This work is the first identification of the molecular components involved specifically in amino acid transport in T. cruzi and provides new insights for further validation of the TcAAAP family as functional permeases.

Arginine and Lysine Transporters Are Essential for Trypanosoma brucei

“…Phylogenetic analyses revealed that the TbAAT5 proteins are homologs of the functionally characterized T . cruzi arginine transporter TcAAAP411 (TcCLB.511411.30 [23]; 76–78% similarity) and TcCAT1.1 to TcCAT1.3 [25] (70–76% similarity), but show a lower degree of similarity to the Leishmania arginine transporter LdAAP3 (LdBPK_310910.1 [6,22]; 60–62% similarity) (Fig 1 and S2 Table). …”

“…cruzi and L . donovani : TcAAAP411, (TcCLB.511411.30 [23]), TcAAP7 (TcCLB.511545.80 [24]), TcCAT1.1, TcCAT1.2, TcCAT1.3 (TcCLB.506153.10, TcCLB.506153.20, TcCLB.506053.10 [25]); LdAAP7 (LdBPK_322800.1 [24]) and LdAAP3 (LdBPK_310910.1 [22]). Further shown are AAP7 in L .…”

“…At saturating arginine concentrations, L-arginine transport mediated by TbAAT5-3 was not affected by the presence of a 10 times excess of the cationic amino acids histidine, ornithine, and lysine, with the latter partially reducing arginine transport only at 100 times excess, indicating high selectivity, comparable to LdAAP3 and TcCAT1.1 [22,25]. Furthermore, like the arginine transporter TcAAAP411 [23], TbAAT5-3 is stereoselective since D-arginine has no effect on arginine transport. The arginine analogs canavanine and homoarginine were inhibitors of TbAAT5-mediated arginine transport, suggesting that the aliphatic chain between the guanidino group and the amino- and the carboxylic acid-group is less important for substrate recognition.…”

“…In contrast, in TcAAAP411-expressing S . cerevisiae cells, canavanine was competing only at 50-fold excess, and for LdAAP3 homoarginine at 5-fold excess did not inhibit arginine uptake [22,23], revealing slight preferences in substrate recognition. The arginine analogs homoarginine and canavanine were not only competitors in heterologous expression systems, but were also the best competitors for arginine uptake in T .…”

“…cruzi TcAAAP411 in Saccharomyces cerevisiae mutants showed high selectivity and high affinity for arginine, i.e. K m of 1.9 μM and 32 μM, respectively [22,23], and the affinity of LdAAP7 for lysine was 7.4 μM [24]. Recently the K m of T .…”