Trypanosoma cruzi proline permease has a unique polyamine co-transport activity

MARTÍNEZ SAYÉ M; REIGADA C; VALERA VERA E; MIRANDA MR; PEREIRA CA

Congreso; XXXI Reunión Anual de la Sociedad Argentina de Protozoología; 2019

Sociedad Argentina de Protozoología

Polyamines are essential compounds to all living cells and in Trypanosoma cruzi, the causative agent of Chagas disease, besides their participation in cell growth and differentiation, its acquisition relies exclusively on transport processes since the parasite is unable to de novo synthesize them. We have previously characterized the proline permease TcAAAP069 and we have identified inhibitors of this transporter that possess trypanocidal activity. In T. brucei the TcAAAP069 orthologue (TbAAT6) mediates the transport of proline and neutral amino acids. In addition, it is responsible for the uptake of the drug eflornithine, a fluoroamino acid containing a putrescine structure, used to treat the Human African Trypanosomiasis. Also, mutant T. cruzi parasites lacking the TcPAT12, a T. cruzi polyamine permease, retain the capacity to transport diamines via a low-affinity mechanism suggesting that there exists another uptake system. Taking all these information into account, we postulated that the proline permease TcAAAP069 could also be responsible for polyamines uptake. In order to test this hypothesis, proline incorporation was competed with increasing concentrations of putrescine. Proline uptake was significantly reduced in the presence of putrescine and this inhibition was dose-dependent. Reciprocally, putrescine incorporation was evaluated in the presence or absence of proline. The uptake was significantly inhibited both in parasites overexpressing TcAAAP069 and wild-type parasites. In silico analysis showed that TbAAT6 and TcAAAP069 have a very similar topology including 11 transmembrane spans, but different to that predicted for TcPAT12. Altogether the results suggest that TcAAAP069 could transport not only proline but also the essential polyamine putrescine, increasing its potential as a target of trypanocidal drugs. However, we cannot rule out the possibility that instead of a co-transport there is a crosstalk that allows a co-regulation of both transporters.