Functional characterization of cationic amino acid transporter, AaCAT3 in the Dengue vector, Aedes aegypti

Aedes aegypti is the major vector of Dengue, Yellow fever and Chikungunya viruses, which put hundreds of millions of people at risk each year in endemic areas. Viral transmission occurs when an infected female mosquito takes blood meal on uninfected humans. Blood meal is indispensable for the mosquito to develop eggs, which completes within 48 hours after blood ingestion. Therefore, nutritional manipulation from blood proteins to egg proteins is critical for mosquito reproduction. Amino acid transport is a part of the process. We cloned a cationic amino-acid transporter in SLC7 family, AaCAT3 from Ae. aegypti. AaCAT3 consists of 5 exons including an additional 5’ exon to current VectoBase predicted gene (AAEL012131). Expression of AaCAT3 in Xenopus laevis oocytes revealed that it selectively transports arginine and lysine. To determine key residues for the transporter activity of AaCAT3, we obtained a putative 3D structure by homology modeling. We introduced point mutations to the key residues and assessed biochemical properties of the mutants in comparison to the wild type. This study reveals functional properties of this understudied amino-acid transporter that may provide clues to develop a novel type of mosquito control strategy.