PIP aquaporin N and C terminals involved in the stability of the tetrameric assembly of the channel

FLORENCIA SCOCHERA; NATALIA GOMEZ; CINTIA JOZEFKOWICZ; GABRIELA AMODEO; ALBERTINA MOGLIONI; KARINA ALLEVA; FLORENCIA MARTINI

Sierra de la Ventana

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

Sociedad Argenina de Biofísica

PIP is an aquaporin subfamily of tetrameric water channels formed by different paralogues, PIP1 and PIP2. PIP2 easily reaches the plasma membrane while PIP1 remains in the cytosol unless is coexpressed with PIP2. This PIP1-PIP2 interaction triggers not only the formation of heterotetrameric assemblies but also regulates its biological activity. We recently showed that PIP2 loop A is a key structural element to control heterotetramerization1 and now we seek for other structural elements involved in homotetramer, or even heterotetramer stabilization. To study PIP´s quaternary structure stabilization through N and C inter-monomeric terminals, we first assayed -by molecular dynamic simulations in an NPT ensemble- the interaction of these terminal peptides corresponding to PIP2 or PIP1 but also the hetero-interaction of PIP2 N-ter with PIP1 C-ter (and viceversa). The interaction energies (as well as specific interactions) showed differences when discriminating the type of PIP analyzed. Interestingly, our preliminary results suggests that the energy interaction between PIP2 N and C intermonomeric terminal is lower than PIP1 one. These results shed light on N and C terminals as relevant elements in the stability of PIP assembly