title: Significance of oxygen transport through aquaporins.
abstract: Aquaporins are membrane integral proteins responsible for the transmembrane transport of water and other small neutral molecules. Despite their well-acknowledged importance in water transport, their significance in gas transport processes remains unclear. Growing evidence points to the involvement of plant aquaporins in CO2delivery for photosynthesis. The role of these channel proteins in the transport of O2and other gases may also be more important than previously envisioned. In this study, we examined O2permeability of various human, plant, and fungal aquaporins by co-expressing heterologous aquaporin and myoglobin in yeast. Two of the most promising O2-transporters (Homo sapiens AQP1 and Nicotiana tabacum PIP1;3) were confirmed to facilitate O2transport in the spectrophotometric assay using yeast protoplasts. The over-expression of NtPIP1;3 in yeasts significantly increased their O2uptake rates in suspension culture. In N. tabacum roots subjected to hypoxic hydroponic conditions, the transcript levels of the O2-transporting aquaporin NtPIP1;3 significantly increased after the seven-day hypoxia treatment, which was accompanied by the increase of ATP levels in the apical root segments. Our results suggest that the functional significance of aquaporin-mediated O2transport and the possibility of controlling the rate of transmembrane O2transport should be further explored.
authors.affiliation: Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2E3, Canada.
authors.forename: Janusz J
authors.initials: JJ
authors.lastname: Zwiazek
authors.affiliation: Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2E3, Canada.
authors.forename: Hao
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2E3, Canada.
authors.forename: Xiangfeng
authors.initials: X
authors.lastname: Tan
authors.affiliation: Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2E3, Canada.|Departamento de Biología Vegetal (Botánica), Facultad de Biología, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Navarro-Ródenas
authors.affiliation: Departamento de Biología Vegetal (Botánica), Facultad de Biología, Universidad de Murcia, Campus de Espinardo, 30100 Murcia, Spain.
authors.forename: Asunción
authors.initials: A
authors.lastname: Morte
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D020346:Aquaporins / Q000378:metabolism*; D001692:Biological Transport; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D009211:Myoglobin / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D018517:Plant Roots / Q000378:metabolism; D011523:Protoplasts / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D050661:Sperm Whale; D014026:Nicotiana / Q000378:metabolism
chemical_list: D020346:Aquaporins; D009211:Myoglobin; D012333:RNA, Messenger; D000255:Adenosine Triphosphate; D010100:Oxygen