Molecular determinants of ammonia and urea conductance in plant aquaporin homologs.
Aquaporins and/or aquaglyceroporins regulate the permeability of plant membranes to water and small, uncharged molecules. Using molecular simulations with a plant plasma membrane aquaporin tetramer, the residues in the channel constriction region were identified as the crucial determinants of ammonia and urea conductance. The impact of these residues was experimentally verified using AtPIP2;1 pore mutants. Several, but not all, mutants with a NIP-like selectivity filter promoted yeast growth on urea or ammonia as sole sources of nitrogen. TIP-like mutants conducted urea but not NH(3), and a residue without direct contact to the pore lumen was critical for conduction in the mutants.
Zentrum für Molekularbiologie der Pflanzen, Pflanzenphysiologie, Universität Tübingen, Auf der Morgenstelle 1, 72076 Tübingen, Germany.
Marek
M
Dynowski
Maria
M
Mayer
Oscar
O
Moran
Uwe
U
Ludewig
D000641:Ammonia / Q000378:metabolism*; D020346:Aquaporins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D003198:Computer Simulation; D004553:Electric Conductivity; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014508:Urea / Q000378:metabolism*
D020346:Aquaporins; D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D010940:Plant Proteins; C110065:major intrinsic protein, plant; C491680:plasma membrane intrinsic protein 2 Arabidopsis; C077491:tonoplast intrinsic protein, plant; D000641:Ammonia; D014508:Urea