Study of structural and functional characteristics of four M. truncatula plant plasma membrane intrinsic proteins

FLORENCIA SCOCHERA; CINTIA JOZEFKOWICZ; AGUSTINA CANESSA FORTUNA; ROMINA FRARE; NICOLAS AYUB; GABRIELA SOTO; KARINA ALLEVA

Salto

Congreso; Latin American Crosstalk in Biophysics and Physiology; 2015

Sociedad Argentina de Biofísica y Seccional Biofísica de la Sociedad Uruguaya de Biociencias

Among plant aquaporin subfamilies, PIP (plasma membrane intrinsicproteins) have been extensively studied during the last decade due to thecapacity of PIP1 and PIP2 paralogues to assembly as homo orheterotetramers. Notwithstanding, structure-function relationships of thissubfamily are still not fully understood.Our previous results show interesting aspects of PIP1 and PIP2 interactionand biological activity regarding PIP first extracellular loop1, N- and Cterminaldomains2, and heterotetrameric stoichiometry3. Our goal is toextend this study to Medicago truncatula aquaporins in order to know ifthese are general features of the PIP AQP subfamily.We assayed four Medicago truncatula PIP (MTR2g094270.1,MTR3g070210.1, MTR4g059390 and MTR5g010150) in the Xenopuslaevis oocytes heterologous expression system. Moreover we performed thecorresponding bioinformatic -phylogenetic and structural- analysis.Our data shows that among the four Medicago truncatula PIP, twocorrespond to the PIP2 group and the others to the PIP1 one.The four PIP present six transmembrane helices and five connecting loops.While N-terminal domains are longer in the two PIP1 in comparison withthe two PIP2, both C-terminal and loop A are shorter.Regarding biological activity, both PIP2 can transport water efficientlywhile PIP1 do not upon expression in Xenopus oocytes.These results are the first steps for a further understanding of PIP structuralmotifs related to their function.