MOLECULAR PHYSIOLOGY AND EVOLUTION OF ESSENTIAL
AMINO ACID TRANSPORT
Up to 90% of the total energy budget in autotrophs is devoted to the synthesis of 20 proteinogenic amino acids. In contrast, animals and other heterotrophs waive synthesis of approximately 10 of the most energetically expensive amino acids, and instead acquire these essential substrates from food or symbiotic resources, subsequently distributing them through a system of electrochemically coupled membrane transporters. We seek to identify such transporters and understand the basic principles behind the evolution, adaptation, and integration of the alimentary absorption and systemic distribution of the essential amino acids. We employ a comprehensive comparative framework of metazoan model organisms with completely sequenced genomes, including those of humans, fruit flies, mosquitoes, and nematodes. Practically, our studies aim to identify organism-specific components of the essential amino acid transport network that can be used as pharmacogenetic targets for correction of metabolic and neuronal disorders in humans, or to selectively suppress pest and pathogen invertebrates. Our experimental approaches include bioinformatics, molecular cloning, heterologous functional expression, electrophysiological and electrochemical assays, structural homology modeling, and reverse genetics.
Molecular physiology of essential amino acid absorption in vector mosquitoes (NIH-NIAID). This study focuses on the members of the Nutrient Amino acid Transporter subfamily of the SLC 6 family (NATs-SLC6, PNAS, 2005). We cloned and characterized a set of NATs that aid in alimentary absorption and systemic distribution of the most underrepresented essential amino acids in mosquitoes. Our present efforts aim to reveal the roles and significances of individual NATs in mosquito biology.
Structural basis of selectivity and druggability of essential amino acid transporters. In this study we employ a unique combination of in silico, in situ, and in vivo assays. AgNAT 3-D model-guided in silico docking is used to sort out the putative blockers of Anopheles NATs from existing libraries of natural and synthetic ligands of SLC6 members. The effects of these inhibitors are tested in situ using heterologous expression of AgNATs, and in vivo using
video-monitoring and image analysis of larval development and behavior.
Cationic amino acid transport in mosquitoes (in collaboration with Immo Hansen, PI). This study aims to reveal the transport functions and biological roles of Cationic Amino acid Transporters belonging to SoLute Carrier family 7 (CAT-SLC7).
RNA interference in Anopheles mosquito larvae. This study aims to develop and optimize a unique technique for systemic, environmental, and tissue specific induction of RNAi in model dipteran insects using fluorescent cell penetrating peptides (CPPs).
Molecular cloning and characterization of amino acid transporters in model nematode, C. elegans. (Graduate student project). The goal of this project is to explore the molecular basis and biological roles of the indispensible Amino acid Transport System (iATS) in the model nematode C. elegans.
Comparative pharmacology of human SLC6 transporters. The goal of this project is to understand differences between, and pharmacophore selectivity of, transporters for canonical neurotransmitters and neuronal transporters of essential amino acids.
2D/3D models, substrate binding pocket, and in situ -in silico profiles of indole- and phenol-branch selective transporters, AgNAT6 and AgNAT8 (see Boudko 2012, JIP).