Abstract
Aquaporin-14 (AQP14) is a newly discovered member of the aquaglyceroporin family, believed to transport both water and small solutes. Its detection in euryhaline teleosts such as Tenualosa ilisha —a species known for dramatic migrations between freshwater and seawater—implies a significant function in maintaining ionic and osmotic balance. However , the detailed structural and mechanistic insights of AQP14 remain largely unexplored at the atomic level. This study leverages extensive all-atom molecular dynamics simulations to elucidate the structure, dynamics, and function of AQP14 from T. ilisha embedded in a physiologically representative phospholipid membrane. A robust homology and AlphaFold3 derived models of Ti AQP14 was constructed and simulated for over one microsecond in a hydrated bilayer comprised of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol . Our simulations reveal a canonical aquaporin fold but identify unique structural features within the extracellular loops and the aromatic/arginine (ar /R) selectivity filter that distinguish it from homologous mammalian aquaglyceroporins. Analysis of the permeation events confirms the channel’s primary function as an efficient water transporter, while the composition and dynamics of the ar/R constriction region suggest a potential for glycerol permeability. Furthermore, we observed key inter-helix interactions and intracellular loop dynamics that contribute to the stability and potential regulatory mechanism of the channel. These findings provide fundamental insights into the molecular basis of solute selectivity and transport in piscine AQP14, offering a crucial step towards understanding its contribution to the extraordinary osmoregulatory capabilities of Hilsa shad. Altogether our work establishes a structural platform for exploration of molecular basis for the exceptional osmoregulatory agility seen in Hilsa shad, and underscores the evolutionary conservation and regulatory complexity of AQP14 in teleosts.