The plasma membrane calcium ATPase activity is modulated by aluminum through its effect on membrane biophysics

MARILINA DE SAUTU1, GUSTAVO SCANAVACHI2, MARIELA S FERREIRA-GOMES1, JUAN PABLO ROSSI1 ROSANGELA ITRI2 AND IRENE C MANGIALAVORI1; .ROSSI, JUAN PABLO F.C.

SANTOS

Congreso; Congress of the Brazilian Biophysical Society; 2019

BRAZILIAN BIOPHYSICAL SOCIETY

The plasmamembrane calcium ATPase activity is modulated by aluminum through its effect onmembrane biophysics Marilina de Sautu1, GustavoScanavachi2, Mariela S Ferreira-Gomes1, Juan Pablo Rossi1 Rosangela Itri2 and Irene C Mangialavori11Cátedra deFisicoquímica Biológica-Departamento de Química Biológica, Universidad deBuenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB)UBA-CONICET. Junín 956, Buenos Aires, Argentina.2 Institute of Physics, University of Sao Paulo (IFUSP)Email:desautu.marilina@gmail.com Aluminum (Al) is environmentally ubiquitous, providing human exposure andit has neurotoxic effects in humans and animals. The mechanisms that havebeen proposed to explain the toxicity of Al are linked to changes in thecellular calcium homeostasis. Recently, we demonstratedthat Al inhibits the plasma membrane calcium ATPase activity by preventing thedephosphorylation of the pump [1]. PMCAis a P-ATPase involved in the regulation of the cell calcium homeostasis. Itsfunction is to transport Ca2+ from cytoplasm towards theextracellular medium against the electrochemical gradient. PMCA like otherintegral membrane proteins operates surrounded by a complex and dynamic lipidbilayer, and the activity of this pump largely depends on the lipids [2]. Inprevious works, we showed that AlCl3 inhibits calcium effluxmediated by PMCA in HEK293T cells [3]. The aim of thiswork is to understand the effect that Al has on the lipid environment of thePMCA. This provide information of the distinctive effect that Al3+would have depends on the lipidic composition of the cell membrane where thePMCA is located. To characterize this effect, mixed micelles of lipids anddetergent (C12E10) were formed in different molarfractions and we measured how the PMCA activity varied and in presence oflipids. Then through SAXS experiments we studied how the lipidic environmentwas changing in the different molar fractions and in the presence of Al. Withan aluminum-specific fluorescent probe (Lumogallion) we evaluate how free aluminumis modified by interacting with the different lipids.The inhibition of the pump by Al depends largely on the lipidssurrounding it. The SAXS experiments results indicate that the biophysicalchanges in the different molar fractions could explain the difference inprotein activity. Moreover, it was demonstrated how aluminum interacts with themicelles, coinciding with lumogallion fluorescence experiments. Acknowledgement: This work was supported by ANCYT PICT 2014 0065,CONICET PIP 0250 and Universidad de Buenos Aires 2014-2017: 20020130100254B,FAPESP, CNPQ and Universidade do Sao Paulo[1] De Sautu M, Saffioti NA, Ferreira-Gomes MS, Rossi RC, Rossi JPFC andMangialavori IC. BBA-Biomembrane (2018) 860(8):1580-1588. doi:10.1016/j.bbamem.2018.05.014[2]Pignataro, M. F., Dodes-Traian, M. M., González-Flecha, F. L., Sica, M.,Mangialavori, I. C., & Rossi, J. P. (2015). Modulation of plasma membraneCa2+-ATPase by neutral phospholipids: effect of the micelle-vesicle transitionand the bilayer thickness. The Journal ofbiological chemistry, 290(10), 6179?6190. doi:10.1074/jbc.M114.