title: Heteromerization of PIP aquaporins affects their intrinsic permeability.
abstract: The plant aquaporin plasma membrane intrinsic proteins (PIP) subfamily represents one of the main gateways for water exchange at the plasma membrane (PM). A fraction of this subfamily, known as PIP1, does not reach the PM unless they are coexpressed with a PIP2 aquaporin. Although ubiquitous and abundantly expressed, the role and properties of PIP1 aquaporins have therefore remained masked. Here, we unravel how FaPIP1;1, a fruit-specific PIP1 aquaporin from Fragaria x ananassa, contributes to the modulation of membrane water permeability (Pf) and pH aquaporin regulation. Our approach was to combine an experimental and mathematical model design to test its activity without affecting its trafficking dynamics. We demonstrate that FaPIP1;1 has a high water channel activity when coexpressed as well as how PIP1-PIP2 affects gating sensitivity in terms of cytosolic acidification. PIP1-PIP2 random heterotetramerization not only allows FaPIP1;1 to arrive at the PM but also produces an enhancement of FaPIP2;1 activity. In this context, we propose that FaPIP1;1 is a key participant in the regulation of water movement across the membranes of cells expressing both aquaporins.
authors.affiliation: Instituto de Biodiversidad y Biología Experimental and Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina.
authors.forename: Agustín
authors.initials: A
authors.lastname: Yaneff
authors.forename: Lorena
authors.initials: L
authors.lastname: Sigaut
authors.forename: Mercedes
authors.initials: M
authors.lastname: Marquez
authors.forename: Karina
authors.initials: K
authors.lastname: Alleva
authors.forename: Lía Isabel
authors.initials: LI
authors.lastname: Pietrasanta
authors.forename: Gabriela
authors.initials: G
authors.lastname: Amodeo
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000737:chemistry* / Q000235:genetics*; D001426:Bacterial Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D031985:Fragaria / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers / Q000737:chemistry; D008164:Luminescent Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008962:Models, Theoretical; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D010539:Permeability; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics*; D055503:Protein Multimerization; D018075:RNA, Complementary / Q000378:metabolism; D014867:Water / Q000737:chemistry; D014982:Xenopus laevis
chemical_list: D020346:Aquaporins; D001426:Bacterial Proteins; D008051:Lipid Bilayers; D008164:Luminescent Proteins; D010940:Plant Proteins; D018075:RNA, Complementary; C110065:major intrinsic protein, plant; C054562:yellow fluorescent protein, Bacteria; D014867:Water