Predicting the functionality of major intrinsic proteins: An in silico analysis in Musa

Major intrinsic proteins (MIPs) are tetrameric complexs with six transmembrane domains. MIPs which are involved in water and nutrient permeability have been called aquaporins and aquaglyceroporins respectivly. Four important subfamilies of MIPs are plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), nodolin-26 like intrinsic proteins (NIPs) and small basic intrinsic proteins (SIPs). Musa sp. from the order Zingiberals is not only the largest supply of food for millions of people but also has tremendous therapeutic properties like ameliorating digestive and metabolic disorders. This species is sensitive to any kind of water deficit. Recently the genomic sequence of Musa acuminata has been determined. Besides the localization of MaMIP genes on the chromosomes and the localization of MaMIP proteins in subcellular compartments, the substrate selectivity of MaMIPs has been determined by dual NPA (Asparagine-Prolin-Alanine) motifs, the ar/R (aromatic/Arginine) selectivity filter and Froger’s position. MaPIP subfamilies were transporters of water, boron, carbon dioxide, hydrogen peroxide and urea. MaTIP subfamilies were transporters of water, hydrogen peroxide, urea and ammonia. MaNIP subfamily has been shown to be transporters of silicon, urea and boron. This functional prediction of the MaMIP roles provides the opportunity to genetically target these passive transporters for the improvement of the species trait.