Abstract - Veit

Phospholipid scramblases facilitate ATP-independent bidirectional movement of lipids between the leaflets of a membrane bilayer. Recent work [1] identified the voltage dependent anion channel (VDAC1) as a scramblase in the outer mitochondrial membrane which plays a major role in importing phospholipids into mitochondria. VDAC1 is active as homodimer, with the lipid scrambling pathway provided by the dimer interface. We developed a fluorescence-based microscopy setup to analyze single vesicles reconstituted with fluorescently labeled lipid transporters [2]. This highthroughput
approach permits parallel analysis of multiple parameters of individual proteoliposomes, including size and protein copy number, with the aim to correlate these features with lipid transport kinetics. Using artificial liposomes containing trace amounts of tail-labeled fluorescent reporter lipids, we were able to monitor the scramblase activity of reconstituted VDAC1 dimers at the single vesicle level and calculate the unitary rate for single dimers.

Sarina Veit (Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Bochum 44801, Germany ), Grace I. Dearden (Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021, USA), Kartikeya M. Menon (Icahn School of Medicine at Mount Sinai, New York, NY 10029), Faria Noor (Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021, USA), Anant K. Menon(Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021, USA), Thomas Günther Pomorski ((Department of Molecular Biochemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum,  Bochum 44801, Germany ; Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark)