In silico and molecular characterization of Q4D1D9_TRYCC, a novel high-molecular weight antigen from Trypanosoma cruzi

GALLARDO, JUAN PABLO; JAVIER SANTOS; NIBORSKI, LETICIA ; MARIANA POTENZA; OSSOWSKI, MICAELA ; KARINA V. MARIÑO; KARINA GOMEZ

Congreso; XXXII Reunión Anual de la Sociedad Argentina de Protozoología; 2020

Chagas illness, a potentially life-threatening disease, is an infection caused by the hemoflagellate parasite Trypanosoma cruzi. By phage display technology, involving cDNA isolated from B cells of patients with chronic Chagas disease (CCC), we selected a recombinant monoclonal antibody, named scFv 6B6, which recognized a protein of 300 kDa only expressed in T. cruzi. Although preliminary, data showed that only plasma from patients with CCC but not those from with Leishmaniasis or non-infected subjects reacted against 6B6 antigen. In this work, immunoprecipitation coupled to mass spectrometry revealed that 6B6 antigen was a hypothetical protein of 323 kDa, named Q4D1D9_TRYCC. According to phylogenetic analysis, this protein is highly conserved throughout evolution in all linages of T. cruzi so far identified but lacks orthologues in other kinetoplastid parasites. In parallel, bioinformatic approaches established that this protein has the most commonly post-translational modifications (acetylation, glycosylation, among others) identified in T. cruzi and the B cell epitopes predictors mapped that almost the entirely protein sequence is immunogenic. Structural predictions using RaptorX server allowed us to foretell six structural domains of Q4D1D9_TRYCC. Interestingly, we found that this protein presents pyrroloquinoline quinone-dependent alcohol dehydrogenase (PQQ) domains, an enzyme function that has not been yet documented in Trypanosomatids. We hypothesize that the enzymatic activity of Q4D1D9_TRYCC may be involved in some detoxification process exerted by the parasite during the mammalian host invasion. To date, our finding allowed the identification of a novel T. cruzi protein as a promising diagnostic candidate for Chagas disease. Moreover, the inhibition of its enzymatic activity could be tested for the development of new drugs against T. cruzi.