Fusion of vesicles into target membranes during many types of regulated exocytosis requires both SNARE-complex proteins and fusogenic lipids, such as phosphatidic acid. Mitochondrial fusion is less well understood but distinct, as it is mediated instead by the protein Mitofusin (Mfn). Here, we identify an ancestral member of the phospholipase D (PLD) superfamily of lipid-modifying enzymes that is required for mitochondrial fusion. Mitochondrial PLD (MitoPLD) targets to the external face of mitochondria and promotes trans-mitochondrial membrane adherence in a Mfn-dependent manner by hydrolysing cardiolipin to generate phosphatidic acid. These findings reveal that although mitochondrial fusion and regulated exocytic fusion are mediated by distinct sets of protein machinery, the underlying processes are unexpectedly linked by the generation of a common fusogenic lipid. Moreover, our findings suggest a novel basis for the mitochondrial fragmentation observed during apoptosis.
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Bonifacino, J. S. & Glick, B. S. The mechanisms of vesicle budding and fusion. Cell 116, 153–166 (2004).
Weber, T. et al. SNAREpins: minimal machinery for membrane fusion. Cell 92, 759–772 (1998).
Vitale, N. et al. Phospholipase D1: a key factor for the exocytotic machinery in neuroendocrine cells. EMBO J. 20, 2424–2434 (2001).
Huang, P., Altshuller, Y. M., Chunqiu Hou, J., Pessin, J. E. & Frohman, M. A. Insulin-stimulated plasma membrane fusion of Glut4 glucose transporter-containing vesicles is regulated by phospholipase D1. Mol. Biol. Cell 16, 2614–2623 (2005).
Di Paolo, G. et al. Impaired PtdIns(4,5)P2 synthesis in nerve terminals produces defects in synaptic vesicle trafficking. Nature 431, 415–422 (2004).
Hales, K. G. & Fuller, M. T. Developmentally regulated mitochondrial fusion mediated by a conserved, novel, predicted GTPase. Cell 90, 121–129 (1997).
Malka, F. et al. Separate fusion of outer and inner mitochondrial membranes. EMBO Rep. 6, 853–859 (2005).
Meeusen, S., McCaffery, J. M. & Nunnari, J. Mitochondrial fusion intermediates revealed in vitro. Science 305, 1747–1752 (2004).
Koshiba, T. et al. Structural basis of mitochondrial tethering by mitofusin complexes. Science 305, 858–862 (2004).
Ishihara, N., Eura, Y. & Mihara, K. Mitofusin 1 and 2 play distinct roles in mitochondrial fusion reactions via GTPase activity. J. Cell Sci. 117, 6535–6546 (2004).
Nakanishi, H. et al. Phospholipase D and the SNARE Sso1p are necessary for vesicle fusion during sporulation in yeast. J. Cell. Sci. 119, 1406–1415 (2006).
Hammond, S. M. et al. Human ADP-ribosylation factor-activated phosphatidylcholine-specific phospholipase D defines a new and highly conserved gene family. J. Biol. Chem. 270, 29640–29643 (1995).
Sung, T. C. et al. Mutagenesis of phospholipase D defines a superfamily including a trans- Golgi viral protein required for poxvirus pathogenicity. EMBO J. 16, 4519–4530 (1997).
Stuckey, J. A. & Dixon, J. E. Crystal structure of a phospholipase D family member. Nature Struct. Biol. 6, 278–284 (1999).
Kanaji, S., Iwahashi, J., Kida, Y., Sakaguchi, M. & Mihara, K. Characterization of the signal that directs Tom20 to the mitochondrial outer membrane. J. Cell Biol. 151, 277–288 (2000).
Leiros, I., Secundo, F., Zambonelli, C., Servi, S. & Hough, E. The first crystal structure of a phospholipase D. Structure Fold Des. 8, 655–667 (2000).
Legros, F., Lombes, A., Frachon, P. & Rojo, M. Mitochondrial fusion in human cells is efficient, requires the inner membrane potential, and is mediated by mitofusins. Mol. Biol. Cell 13, 4343–4354 (2002).
Chen, H. et al. Mitofusins Mfn1 and Mfn2 coordinately regulate mitochondrial fusion and are essential for embryonic development. J. Cell Biol. 160, 189–200 (2003).
Chen, H., Chomyn, A. & Chan, D. C. Disruption of fusion results in mitochondrial heterogeneity and dysfunction. J. Biol. Chem. 280, 26185–26192 (2005).
Cable, M. B., Jacobus, J. & Powell, G. L. Cardiolipin: a stereospecifically spin-labeled analogue and its specific enzymic hydrolysis. Proc. Natl Acad. Sci. USA 75, 1227–1231 (1978).
Liu, J. et al. Phospholipid scramblase 3 controls mitochondrial structure, function, and apoptotic response. Mol. Cancer Res. 1, 892–902 (2003).
Hovius, R., Thijssen, J., van der Linden, P., Nicolay, K. & de Kruijff, B. Phospholipid asymmetry of the outer membrane of rat liver mitochondria. Evidence for the presence of cardiolipin on the outside of the outer membrane. FEBS Lett. 330, 71–76 (1993).
Cao, J., Liu, Y., Lockwood, J., Burn, P. & Shi, Y. A novel cardiolipin-remodeling pathway revealed by a gene encoding an endoplasmic reticulum-associated acyl-CoA:lysocardiolipin acyltransferase (ALCAT1) in mouse. J. Biol. Chem. 279, 31727–31734 (2004).
Karbowski, M. et al. Quantitation of mitochondrial dynamics by photolabeling of individual organelles shows that mitochondrial fusion is blocked during the Bax activation phase of apoptosis. J. Cell Biol. 164, 493–499 (2004).
Esposti, M. D., Cristea, I. M., Gaskell, S. J., Nakao, Y. & Dive, C. Proapoptotic Bid binds to monolysocardiolipin, a new molecular connection between mitochondrial membranes and cell death. Cell Death. Differ. 10, 1300–1309 (2003).
Kagan, V. E. et al. Cytochrome c acts as a cardiolipin oxygenase required for release of proapoptotic factors. Nature Chem. Biol. 1, 223–232 (2005).
Neutzner, A. & Youle, R. J. Instability of the mitofusin Fzo1 regulates mitochondrial morphology during the mating response of the yeast Saccharomyces cerevisiae. J. Biol. Chem. 280, 18598–18603 (2005).
Nakanishi, H., de los Santos, P. & Neiman, A. M. Positive and negative regulation of a SNARE protein by control of intracellular localization. Mol. Biol. Cell 15, 1802–1815 (2004).
Vicogne, J. et al. Asymmetric phospholipid distribution drives in vitro reconstituted SNARE-dependent membrane fusion. Proc. Natl Acad. Sci. USA doi: 10.1073/pnas0606881103 (2006).
Zuchner, S. et al. Mutations in the mitochondrial GTPase mitofusin 2 cause Charcot-Marie-Tooth neuropathy type 2A. Nature Genet. 36, 449–451 (2004).
Kuhlenbaumer, G., Young, P., Hunermund, G., Ringelfstein, B. & Stogbauer, F. Clinical features and molecular genetics of hereditary peripheral neuropathies. J. Neurol. 249, 1629–1650 (2002).
We thank U. Moll, C. Kisker, J. C. Hsieh, G. Rodomen, S. Van Horn, M. Fuller, M. Rojo, R. J. Youle, D. Bogenhagen, J. Vicogne, A. Neiman, G. Du, S. Tsirka and members of the Frohman lab for technical advice and assistance, reagents and critical discussions. The work was supported by awards National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK; 64166) and National Institute of General Medical Sciences (NIGMS; 71520) to M.A.F., a National Research Service Award (NRSA) T32 fellowship to G.M.J., and a fellowship award to S.Y.C. from the United Mitochondrial Disease Foundation.
The authors declare no competing financial interests.
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Choi, S., Huang, P., Jenkins, G. et al. A common lipid links Mfn-mediated mitochondrial fusion and SNARE-regulated exocytosis. Nat Cell Biol 8, 1255–1262 (2006) doi:10.1038/ncb1487
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