Plant Aquaporins

Abstract

This mini-review briefly presents the main types of plant aquaporins, highlighting their importance for different plant species and for plant cellular functions. Aquaporins (AQPs), families of water channel proteins (WCPs) are transmembrane proteins that are present in prokaryotes, animals, plants, and humans. The plant aquaporins are part of the Major Intrinsic Proteins (MIPs) family which resides in the following plant organs: roots, stems, leaves, flowers, fruits, and seeds. According to the sub-cellular localization, to their sequence homologies and to their phylogenetic distribution, plant aquaporins have been divided in five subgroups: (a) plasma membrane intrinsic proteins (PIPs); (b) tonoplast intrinsic proteins (TIPs); (c) Nodulin26-like intrinsic membrane proteins (NIPs); (d) small basic intrinsic proteins (SIPs) and (e) uncharacterized intrinsic proteins (XIPs). Different subclasses of the plant aquaporins allow several types of transport using: water, glycerol, urea, hydrogen peroxide, organic acids, ethanol, methanol, arsenite, lactic acid, and gaseous compounds. Plant aquaporins have a significant role in cell response to cold stress, photosynthesis, plant growth, cell elongation, reproduction, and seed germination.

Genome-wide analysis of the aquaporin genes in melon (Cucumis melo L.)

“…NPA motifs have a critical function in proton exclusion and as a size barrier. The second constriction, known as the aromatic/arginine (ar/R) selectivity filter, is formed at the extracellular vestibule by four residues, one each in helices 2 and 5 (H2, H5) and two in Loop E (LE1 and LE2), and is the narrowest part of the pore in most of the aquaporin homologues 7 that give rise to the possibility of transporting different specific molecules while serving as an exclusion barrier for others 8 (for a review, see Luang and Hrmova, 2017) 3 . However, in addition to these two well-known filters, other amino acid residues have been shown to be important in the discrimination between the transport of molecules, the Froger’s positions (FPs) 9 located in Loop C (P1), Loop E (P2–P3) and transmembrane helix 6 (P4–P5).…”

Nanoencapsulated Boron Foliar Supply Increased Expression of NIPs Aquaporins and BOR Transporters of In Vitro Ipomoea batatas Plants

“…Aquaporins perform a main role to enable facilitated passive transport, down their concentration gradients, of basically water; however, the capacity of some aquaporin isoforms to facilitate the transport of a broad spectrum of small molecules, such as urea, ammonia, silicon, carbon dioxide, hydrogen peroxide, boron, among many others, has been widely studied [10]. It has been proved that the specificity of molecule transport through different aquaporins isoforms is mostly controlled by the steric occlusion that specific residues provide, and some of the widely described important positions are NPA motifs, ar/R selectivity filters, and Froger's positions (FP) [11][12][13].…”