The mechanism of biomembrane fission

We have studied the mechanism of Golgi transport carrier formation (cooperation with Prof. Alberto Luini, Chieti, It; see Weigert et al., 1999), in comparison to endocytic vesicle formation (see Burger et al., 2000). Our aim was to determine the exact role of proteins and lipids in membrane fission, and formulate a first comprehensive molecular model of biomembrane fission (see Burger, 2000; Kooijman et al., 2003; Shemesh et al., 2003). 

Membrane fission was reconstituted in lipid model systems with the aim to determine the exact role of proteins and lipids, and to provide a detailed morphological description of membrane fission using state of the art electron microscopy (fast or high-pressure freezing, freeze substitution – thin sectioning, freeze fracture, cryoEM, EM-tomography and 3D-reconstruction). EM analysis of membrane fission in model and biological systems was combined with the biophysical and biochemical characterization of the key lipids and protein-lipid interactions (cooperation with Prof. Ben de Kruijff, Utrecht, NL; see Burger et al., 2000; and Kooijman et al., 2003, 2004).

Membrane lipid domains and a local change in lipid composition are likely to play a central role in the regulation of membrane curvature and the induction of membrane fission. One of our goals was to explore the possibilities of non-linear microscopy - based on coherent anti-Stokes Raman scattering (CARS) - to visualise and characterise on a microscopic scale the spatial heterogeneities (domains) that exist in the lipid composition of biomembranes (cooperation with Dr. Michiel Müller, University of Amsterdam, NL, and Prof. Ben de Kruijff, Utrecht, NL). At a later stage we have applied the same technology to study the lipid composition of individual lipid droplets (Rinia et al., 2007, 2008).

Background on CARS microscopy

The aims of the experiments described above was to improve our understanding of the molecular mechanism of biomembrane fission, in general, and in Golgi and endocytic membrane fission in particular. Moreover, we have used our experimental findings to develop a theoretical model of biomembrane fission taking into account the elastic properties of lipid bilayers, as well as protein-lipid interactions (cooperation with Dr. Misha Kozlov, Tel Aviv, Is; see Shemesh et al., 2003).

Link to our HFSP network on Membrane Fission

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References

Burger, K.N.J. (2000). Greasing membrane fusion and fission machineries. Traffic 1:605-613. 

Burger, K.N.J., R.A. Demel, S.L. Schmid, and B. de Kruijff (2000). Dynamin is membrane-active: lipid insertion is induced by phosphoinositides and phosphatidic acid. Biochemistry 39:12485-12493. 

Kooijman, E.E., V. Chupin, B. de Kruijff, and K.N.J. Burger (2003). Modulation of Membrane Curvature by Phosphatidic Acid and Lysophosphatidic Acid. Traffic 4:162-174.

Kooijman, E.E., V. Chupin, N.L. Fuller, M.M. Kozlov, B. de Kruijff, K.N.J. Burger and P.R. Rand (2005). Spontaneous curvature of phosphatidic acid and lysophosphatidic acid. Biochemistry 44:2097-2102.

Shemesh, T., A. Luini, V. Malhotra, K.N.J. Burger, and M.M. Kozlov (2003). Pre-fission constriction of Golgi tubular carriers driven by local lipid metabolism: a theoretical model. Bioph. J. 85:3813-3827.

Weigert, R., M.G. Silletta, S. Spano, G. Turacchio, C. Cericola, A. Colanzi, S. Senatore, R. Mancini, E.V. Polishchuk, M. Salmona, F. Facchiano, K.N.J. Burger, A. Mironov, A. Luini, and D. Corda (1999). CtBP/BARS induces fission of Golgi membranes by acylating lysophosphatidic acid. Nature 402:429-433.

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