EISOSOMES AND PLASMA MEMBRANE ORGANIZATION

AGUSTINA OLIVERA-COUTO; VALENTINA SALZMAN; MILAGROS MAILHOS; ENRICO GRATON ; PABLO S. AGUILAR

Filadelfia

Congreso; 57 Annual Meeting of the Biophysical Society; 2013

Biophysical Society

A vast body of evidence coming from different microscopy techniques has been instrumental in concluding the 10-year-long debate on whether biological membranes presented lateral segregation of proteins and lipids. Currently, the existence of membrane domains in both eukaryotes and prokaryotes has been common ground. However, the mechanisms that sustain membrane domain formation and maintenance remain largely unknown. Our work is focused on the study of Eisosomes, recently discovered plasma membrane domains in S. cerevisiae. We showed that Pil1 and Lsp1, the major proteinaceous components of eisosomes, are able to form self-assemblies that bind and curve membranes both in vivo and in vitro. We also showed that Lsp1 and Pil1 membrane-sculpting abilities are associated with the generation and organization of membrane domains (2). Thus, our currently published work support the hypothesis that a mechanism for membrane eisosome domain formation is membrane curvature generation directed by Pil1-Lsp1 assemblies. To address this hypothesis we are applying Fluorescence Correlation Spectroscopy and Number and Brightness Analysis to describe the dynamics of Pil1 and Lsp1 in vivo. We are studying the oligomeric state and concentration of these proteins in the cytoplasmic soluble fraction and in the Eisosomes. Also we are exploring the diffusion constant and the kinetic parameters of binding and dissociation of Pil1 and Lsp1 from the Eisosome, both in stationary fase and during Eisosome formation in mitosis cell division.