title: Intracellular pH sensing is altered by plasma membrane PIP aquaporin co-expression.
abstract: The plant plasma membrane barrier can express aquaporins (PIP1 and PIP2) that show two intriguing aspects: (1) the potential of modulating whole membrane water permeability by co-expression of both types, which have recently been distinguished for showing a different capacity to reach the plasma membrane; and (2) the faculty to reduce water permeation through the pore after cytosolic acidification, as a consequence of a gating process. Our working hypothesis is that these two key features might enhance plasticity of the membrane water transport capacity if they jointly trigger any cooperative interaction. In previous work, we proved by biophysical approaches that the plasma membrane of the halophyte Beta vulgaris storage root presents highly permeable aquaporins that can be shut down by acidic pH. Root Beta vulgaris PIPs were therefore subcloned and expressed in Xenopus oocytes. Co-expression of BvPIP1;1 and BvPIP2;2 not only enhances oocyte plasma membrane water permeability synergistically but also reinforces pH inhibitory response from partial to complete shut down after cytosolic pH acidification. This pH dependent behavior shows that PIP1-PIP2 co-expression accounts for a different pH sensitivity in comparison with PIP2 expression. These results prove for the first time that PIP co-expression modulates the membrane water permeability through a pH regulatory response, enhancing in this way membrane versatility to adjust its water transfer capacity.
authors.affiliation: Departamento de Fisiología, Universidad de Buenos Aires, Argentina.
authors.forename: Jorge
authors.initials: J
authors.lastname: Bellati
authors.forename: Karina
authors.initials: K
authors.lastname: Alleva
authors.forename: Gabriela
authors.initials: G
authors.lastname: Soto
authors.forename: Victoria
authors.initials: V
authors.lastname: Vitali
authors.forename: Cintia
authors.initials: C
authors.lastname: Jozefkowicz
authors.forename: Gabriela
authors.initials: G
authors.lastname: Amodeo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D027461:Beta vulgaris / Q000235:genetics / Q000378:metabolism*; D002463:Cell Membrane Permeability; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D005260:Female; D015870:Gene Expression; D017343:Genes, Plant; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014867:Water / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D020346:Aquaporins; D017931:DNA Primers; D018744:DNA, Plant; D010940:Plant Proteins; D011994:Recombinant Proteins; D014867:Water