Aquaporin channel heterotetramerization studied by dimeric tandem subunits

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

Carlos Paz

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

Sociedad Argentina de Biofisica

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.