Lateral Dynamics of Proteins with Polybasic Domain on Anionic Membranes: A Dynamic Monte-Carlo Study

Department presentation given at the University of Edinburgh, Edinburgh, UK

Transcript

1. Lateral dynamics of proteins with polybasic domain on anionic membranes: A dynamic Monte-Carlo study Vladimir Kiselev PhD student The University of Edinburgh CSBE seminar, Edinburgh, UK 18 November 2010
2. Electrostatics in protein- membrane interactions 20-40% +++++ +++++ +++++ +++++ PA, PS (-1) PIP2 (-4)
3. Example: proteins with polybasic domain c-Src MARCKS Murray D. et al. Structure (London, England : 1993) 5, no. 8 (August 1997): 985-9 Gambhir A. et al. Biophysical journal 86, no. 4 (April 2004): 2188-207
4. Endocytosis Arf6 (+) ARNO PIP2 (-4) PLD PA (-1) PIP5K AP-2 Gundelfinger E. et al. Nature reviews. Molecular cell biology 4, no. 2 (March 2003): 127-39 •  Spatial dimension: ~100 nm •  Time: ~1 s •  Feedback loops (↑+,↑-) •  Electrostatics (+,-)
5. Lipid gradients in endocytosis PLD Zeniou-Meyer M. et al. The Journal of biological chemistry 282, no. 30 (July 2007): 21746-57 PI4P PIP2 PIP5K ATP ADP Iman van den B. and Nullin Divecha. Journal of cell science 122, no. Pt 21 (November 2009): 3837-50 Free choline Water Membrane - - - - - - - - - + + -
6. Model setup d=0.8nm
7. PS (-1) is weakly sequestered by the peptide PS (-1) density At 25-35% PS the peptide is enriched with PS only by 1.3 No PIP2 Weak sequestration of PS lipids on binary membranes Exp
8. PIP2 (-4) is strongly sequestered by the peptide PIP2 (-4) density At 1% PIP2 the peptide is enriched with PIP2 by 10 The peptide sequesters mainly PIP2 lipids, but not PS Exp
9. PIP2 drastically changes electrostatic properties of peptide On binary PC/PS membranes the peptide is always positive Already at 0.2% PIP2 the peptide becomes negative Peptide total charge
10. The peptide diffuses mainly with PIP2 lipids but not with PS Average association time of lipids bound to the peptide Exp
11. Presence of PIP2 reduces the peptide diffusion rate Binary Ternary Exp Exp
12. What happens if there is a lipid gradient on the membrane? Peptide charge Value of gradient Peptide diffusion coefficient PLD PLD
13. Simulations are in agreement with analytical estimations Relevant biological conditions: V = 3 µm/s ~ 10 µm Cell Time Displacement
14. Addition of PIP2 switches the effect PIP2
15. Continuous model 30% t = 0.2 s 13.3 times •  Dimension: ~100 nm •  Time: ~1 s Endocytosis
16. Conclusions •  Model predicts formation of a “lipid shell” in the vicinity of the PB •  PB domain sequesters mainly PIP2 lipids, but not PA or PS •  PB diffusion rate weakly depends on undisturbed membrane composition •  In the presence of lipid gradient PB drifts in the region of higher lipid density – spontaneous clustering
17. Future work 1) Extending the continuous model by including: –  protein membrane-cytoplasmic shuttling –  local lipid production –  protein phosphorylation/dephosphorylation 2) Modelling of endocytic triggering and feedback loops
18. Thank you Acknowledgements Dr. Andrew Goryachev CSBE, UoE Dr. Davide Marenduzzo School of Physics, UoE Prof. Sir Kenneth Murray The Darwin Trust of Edinburgh $
19. Experimental evidence Golebiewska et al., Mol Biol Cell 19:1663-1669, 2008 Golebiewska et al., Biophys J 91:588-599, 2006 FCS Fluorescence quenching experiments