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Curr Biol. 2016 Mar 7;26(5):627-39. doi: 10.1016/j.cub.2016.01.011. Epub 2016 Feb 18.

AtMic60 Is Involved in Plant Mitochondria Lipid Trafficking and Is Part of a Large Complex.

Author information

1
Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168 CNRS-CEA-INRA-Université Grenoble Alpes, 38000 Grenoble, France. Electronic address: morganemichaud71@gmail.com.
2
Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168 CNRS-CEA-INRA-Université Grenoble Alpes, 38000 Grenoble, France.
3
Laboratoire de Biologie à Grande Echelle, U1038 CEA-INSERM-Université Grenoble Alpes, 38000 Grenoble, France.
4
Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
5
Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
6
Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168 CNRS-CEA-INRA-Université Grenoble Alpes, 38000 Grenoble, France. Electronic address: juliette.jouhet@cea.fr.

Abstract

The mitochondrion is an organelle originating from an endosymbiotic event and playing a role in several fundamental processes such as energy production, metabolite syntheses, and programmed cell death. This organelle is delineated by two membranes whose synthesis requires an extensive exchange of phospholipids with other cellular organelles such as endoplasmic reticulum (ER) and vacuolar membranes in yeast. These transfers of phospholipids are thought to occur by a non-vesicular pathway at contact sites between two closely apposed membranes. In plants, little is known about the biogenesis of mitochondrial membranes. Contact sites between ER and mitochondria are suspected to play a similar role in phospholipid trafficking as in yeast, but this has never been demonstrated. In contrast, it has been shown that plastids are able to transfer lipids to mitochondria during phosphate starvation. However, the proteins involved in such transfer are still unknown. Here, we identified in Arabidopsis thaliana a large lipid-enriched complex called the mitochondrial transmembrane lipoprotein (MTL) complex. The MTL complex contains proteins located in the two mitochondrial membranes and conserved in all eukaryotic cells, such as the TOM complex and AtMic60, a component of the MICOS complex. We demonstrate that AtMic60 contributes to the export of phosphatidylethanolamine from mitochondria and the import of galactoglycerolipids from plastids during phosphate starvation. Furthermore, AtMic60 promotes lipid desorption from membranes, likely as an initial step for lipid transfer, and binds to Tom40, suggesting that AtMic60 could regulate the tethering between the inner and outer membranes of mitochondria.

PMID:
26898467
PMCID:
PMC6322921
DOI:
10.1016/j.cub.2016.01.011
[Indexed for MEDLINE]
Free PMC Article

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