Deeping inside a plasma membrane strawberry aquaporin with high water capacity transport

CAVIGLIA, AGUSTÍN F.; GUASTAFERRI, FLORENCIA V.; ALVEAR ARIAS, JUAN JOSÉ; FERNÁNDEZ, MIGUEL; CARMONA, EMERSON; AMODEO, GABRIELA; GONZÁLEZ, CARLOS; GARATE, JOSÉ ANTONIO; OZU, MARCELO

Congreso; RAFV Conference 2021 - XXXIII Argentinian meeting of Plant Physiology; 2021

We have previouslydemonstrated in strawberry that FaPIP2;1, a plasma membrane intrinsic (PIP)aquaporin, is not only present but also shows an expression pattern thatincreases with ripening. The sequence of FaPIP2;1 presents motifs that arecompatible with pH regulation, phosphorylation and methylation. Experiments in Xenopus oocytes demonstrated thatFaPIP2;1 shows high water permeability (Pf) values that can beregulated by cellular acidification, phosphorylation and heteromerizationevents. Here we show that the transport capacity of FaPIP2,1 is higher than inother AQPs and that heteromerization modifies the sensitivity of FaPIP2;1 tomembrane tension changes. This regulatory mechanism that has not been observedbefore in PIP members is characterized by non-linear relationships betweenwater fluxes (Jw) and the applied osmotic gradients (𝛥osm). The comparison to other mechanosensitive aquaporins shows that thePf decrease in FaPIP2;1 is more sensitive to the membrane tensionchanges associated with volume increments. Furthermore, since the highwater-transport capacity of FaPIP2;1 is a feature that has not been addressedat the molecular level we employ Molecular Dynamic (MD) simulations to predicthow the water molecule moves through the permeable pathway. Here we show theresults of 1 𝜇ssimulations with a homology model of FaPIP2;1 developed with the crystalstructure of SoPIP2;1 (PDB 2B5F). Our results indicate that in comparison toother aquaporins the water load capacity in the channel of FaPIP2;1 is high,which could explain its high transport rate.