Chagas disease is transmitted to humans by obligatory hematophagous insects of Triatominae subfamily, which feeds on various hosts to acquire their nutritional sustenance derived from blood proteins. Hemoglobin digestion is a pivotal metabolic feature of triatomines, representing a key juncture in their competence toward Trypanosoma cruzi; however, it remains poorly understood. To explore the hemoglobin digestion pathway in Rhodnius prolixus, a major Chagas disease vector, we employed an array of approaches for activity profiling of various midgut-associated peptidases using specific substrates and inhibitors. Dissecting the individual contribution of each peptidase family in hemoglobin digestion, has unveiled a predominant role played by aspartic proteases and cathepsin B-like peptidases. Determination of peptidase-specific cleavage sites of these key hemoglobinases, in conjunction with mass spectrometry-based identification of in vivo Hb-derived fragments, has revealed the intricate network of peptidases involved in the Hb digestion pathway. This network is initiated by aspartic proteases and subsequently sustained by cysteine proteases belonging to the C1 family. The process is continued simultaneously by amino- and carboxypeptidases. The comprehensive profiling of midgut-associated aspartic proteases by quantitative proteomics has enabled the accurate revision of gene annotations within the A1 family of the R. prolixus genome. Significantly, this study definitely illuminated the obscured role of the anterior midgut in blood digestion. The unveiling of this catabolic pathway holds immense promise for the identification of novel targets aimed at controlling the transmission of Chagas disease.
Keywords: Disease vectors; Ectoparasites; Hematophagy; Protein digestion; Trypanosoma cruzi.
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