Measurement of Lipid Transport in Mitochondria by the MTL Complex.

Membrane biogenesis requires an extensive traffic of lipids between different cell compartments. Two main pathways, the vesicular and non-vesicular pathways, are involved in such a process. Whereas the mechanisms involved in vesicular trafficking are well understood, fewer is known about non-vesicular lipid trafficking, particularly in plants. This pathway involves the direct exchange of lipids at membrane contact sites (MCSs) between organelles. In plants, an extensive traffic of the chloroplast-synthesized digalactosyldiacylglycerol (DGDG) to mitochondria occurs during phosphate starvation. This lipid exchange occurs by non-vesicular trafficking pathways at MCSs between mitochondria and plastids. By a biochemical approach, a mitochondrial lipoprotein super-complex called MTL (Mitochondrial Transmembrane Lipoprotein complex) involved in mitochondria lipid trafficking has been identified in Arabidopsis thaliana. This protocol describes the method to isolate the MTL complex and to study the implication of a component of this complex (AtMic60) in mitochondria lipid trafficking.