Aquaporin channel heterotetramerization studied by dimeric tandem subunits.

JOZEFKOWICZ CINTIA; SCOCHERA FLORENCIA; SIGAUT LORENA; PIETRASANTA LIA ISABEL; AMODEO GABRIELA; ALLEVA KARINA

Córdoba

Congreso; XLII Reunión Anual de la Sociedad Argentina de Bofisica; 2013

Sociedad Argentina de Biofísica (SAB)

Research done in the last years strongly supports the hypothesis that certain plant plasma membrane aquaporin (PIP) can form heterooligomeric assemblies, specially combining PIP2 and PIP1 subunits. We have already confirmed the existence of PIP heterotetramers by studying structural elements involved in the ruling of homo versus heterotetramerization organization between Beta vulgaris PIP aquaporins (1). To further investigate the biophysical properties of PIP1-PIP2 heterotetramerization process, and as the assembly of some aquaporins seemed to proceed as a dimerization of dimers (2), we co-inject a series of cRNA tandem constructs encoding for covalently linked BvPIP1;1 and BvPIP2;2. The constructions expressed in the plasma membrane of Xenopus oocytes formed by tandem dimers show identical biophysical characteristics, i.e. osmotic water coefficient (Pf) and pH regulation, than the co-expressed individual subunits. Our results show for the first time that PIP1-PIP2 dimers can form functional heterotetrameric channels. Acknowledgements: This work was financed by PICT 10-02042, CONICET PIP 0190 & UBACYT 2013 0159 grants to K.A and UBACyT11-14 y PICT11-2239 to GA.