IQUIFIB   02644
INSTITUTO DE QUIMICA Y FISICOQUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Leucine residue involved in PIP aquaporin gating
Autor/es:
ALLEVA, KARINA; ALIPERTI CAR, LUCIO; GONZALEZ FLECHA, LUIS; ARI, ZEIDA; VITALI, VICTORIA ANDREA; ZERBETTO DE PALMA, GERARDO; CANESSA FORTUNA, AGUSTINA; ESTRIN, DARIO A.
Lugar:
California
Reunión:
Congreso; 62nd Annual meeting Biophysical Society; 2018
Resumen:
PIPs are channels from the aquaporin family mediating water transport in plant plasma membranes. Intracellular proton concentration modulates the water permeability of these channels in a cooperative way, with lower water transport at high proton concentration (Jozefkowicz et al., Biophysical Journal 2016). The participation of a conserved histidine residue located in loopD has been revealed, both by mutational studies and by structural data (Tournaire-Roux et al., Nature 2003, Törnroth-Horsefield et al., Nature 2006), as a key element in the gating of these channels. However, after crystallization of SoPIP2;1, it has been suggested that hydrophobic residues do also participate in the closing of PIP pores. In this work we faced molecular dynamic simulations and heterologous expression studies to unveil the involvement of Leu206 or Leu197 in the regulation of water transport in BvPIP2;2 and SoPIP2;2 respectively. Alterations of channel radius were traced when leucine residue is replaced by alanine showing that the presence of this hydrophobic residue is needed to create a constriction in the water pore. Experiments expressing both wild type and mutant PIP channels in Xenopus ovocytes show that mutant PIP lacks the characteristic pH sensitivity to cytoplasmic proton concentration thereby supporting the in silico results. This work adds a step in the clarification of the strictly controlled gating mechanism of PIP channels whose elucidation contribute to the understanding of channels dynamics and functioning.