IBBEA   24401
INSTITUTO DE BIODIVERSIDAD Y BIOLOGIA EXPERIMENTAL Y APLICADA
Unidad Ejecutora - UE
artículos
Título:
PIP Water Transport and Its pH Dependence Are Regulated by Tetramer Stoichiometry
Autor/es:
JOZEFKOWICZ CINTIA; SOTO GABRIELA; AMODEO GABRIELA; SCOCHERA FLORENCIA; PIETRASANTA LIA ISABEL; ALLEVA KARINA; SIGAUT LORENA; AYUB NICOLAS; GONZALEZ FLECHA LUIS
Revista:
BIOPHYSICAL JOURNAL
Editorial:
CELL PRESS
Referencias:
Lugar: United States; Año: 2016 vol. 110 p. 1312 - 1321
ISSN:
0006-3495
Resumen:
Many plasma membrane channels form oligomeric assemblies, and heterooligomerization has been described asa distinctive feature of some protein families. In the particular case of plant plasma membrane aquaporins (PIPs), PIP1 and PIP2monomers interact to form heterotetramers. However, the biological properties of the different heterotetrameric configurationsformed by PIP1 and PIP2 subunits have not been addressed yet. Upon coexpression of tandem PIP2-PIP1 dimers in Xenopusoocytes, we can address, for the first time to our knowledge, the functional properties of single heterotetrameric species having2:2 stoichiometry. We have also coexpressed PIP2-PIP1 dimers with PIP1 and PIP2 monomers to experimentally investigatethe localization and biological activity of each tetrameric assembly. Our results show that PIP2-PIP1 heterotetramers canassemble with 3:1, 1:3, or 2:2 stoichiometry, depending on PIP1 and PIP2 relative expression in the cell. All PIP2-PIP1 heterotetramericspecies localize at the plasma membrane and present the same water transport capacity. Furthermore, the contributionof any heterotetrameric assembly to the total water transport through the plasma membrane doubles the contribution of PIP2homotetramers. Our results also indicate that plasma membrane water transport can be modulated by the coexistence ofdifferent tetrameric species and by intracellular pH. Moreover, all the tetrameric species present similar cooperativity behaviorfor proton sensing. These findings throw light on the functional properties of PIP tetramers, showing that they have flexiblestoichiometry dependent on the quantity of PIP1 and PIP2 molecules available. This represents, to our knowledge, a novelregulatory mechanism to adjust water transport across the plasma membrane.