Characterization of a blood-meal-responsive proton-dependent amino acid transporter in the disease vector, Aedes aegypti

After anautogenous mosquitoes ingest the required blood meal, proteins in it are rapidly cleaved, yielding a large pool of amino acids. Transport of these amino acids into gut epithelial cells and their subsequent translocation into other tissues is critical for oogenesis and other physiological processes. We have identified a proton amino acid transporter (PAT) in Aedes aegypti (AaePAT1, AAEL007191) which facilitates this transport and is expressed in epithelial cell membranes of larval caecae and the adult midgut. AaePAT1 encodes a 475 amino acid protein showing high similarity to Anopheles gambiae AGAP009896, Culex pipiens CPIJ011438 and Drosophila melanogaster CG7888. When expressed in Xenopus oocytes the transport kinetics showed AaePAT1 is a low affinity transporter with low substrate specificity, having Km and Vmax values of about 7.2 mmol l(-1) and 69 pmol oocyte(-1) min(-1), respectively, for glutamine. A number of other amino acids are also transported by this PAT. In female adult midgut, AaePAT1 transcript levels were induced after ingestion of a blood meal.