Plant aquaporins PIP2 and TIP2 show different responses to membrane deformation

GOLDMAN, RAMIRO PABLO; JOZEFKOWICZ, C.; SUTKA, M.; ALLEVA, K.; OZU, MARCELO

Bahía Blanca

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Biofísca; 2014

Sociedad Argentina de Biofísica

In this work we studied the mechanosensitive properties of PIP2 and TIP2, both aquaporins (AQPs) from Beta vulgaris (beetroot). We expressed the proteins in Xenopus oocyte membranes and tested their functionality applying different osmotic gradients by means of the emptied-out oocyte technique [1]. The results obtained with TIP2 show that the relationship between water flux (JW) and the osmotic gradient (DOsm) is similar to that observed with human AQP1 [2]. However, this seems not to be the case for PIP2. These results would be reflecting differences between the sensibility of TIPs and PIPs to changes of membrane tension. In the case of TIP2, the osmotic permeability coefficient (Pf) decreases with increasing DOsm. This indicates that the closure of the water pore could be a cooperative phenomenon, occurring in TIPs in a similar way as in hAQP1 [2]. In conclusion, present results show that a closure mechanism gated by increasing membrane tension is present in plant AQPs, as occur in animal members of the family.