RELEASE OF CONTENT THROUGH MECHANO- SENSITIVE GATES IN PRESSURISED - - PowerPoint PPT Presentation
RELEASE OF CONTENT THROUGH MECHANO- SENSITIVE GATES IN PRESSURISED LIPOSOMES Martti Louhivuori University of Groningen M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010 www.cgmartini.nl M ARTINI coarse-grained model M. Louhivuori / ISSP
Martti Louhivuori University of Groningen
www.cgmartini.nl
interaction sites
DPPC cholesterol peptide ALYWK water butane
C1 SC1 SC3 SP1 Qa Qo Na C1 SC4 P4 C1 C5 SNd SC4 SC4 Qd SP1 C3 No
experimental thermodynamic data nonbonded interactions atomistic MD simulations bonded interactions
bonded interactions
angle distribution
nonbonded interactions
Rhombohedral phase (experimentally observed for DOPC/DOPE 3:1 and 2:1 Lyan & Huang, 2002)
side view top view
THE VALIDATION THE VALIDATION
comparing to experimental measurements
Reproduced in CG simulation (Marrink & Mark, Biophys. J., 2004)
bilayers rafts sugars membrane proteins vesicles vesicles w/ proteins
bilayers rafts sugars membrane proteins vesicles vesicles w/ proteins
interaction sites
DPPC cholesterol peptide ALYWK water butane
C1 SC1 SC3 SP1 Qa Qo Na C1 SC4 P4 C1 C5 SNd SC4 SC4 Qd SP1 C3 No
SPEED shortrange interactions large timestep few degrees of freedom GENERAL consistent modeling biomolecular systems easily extended EASE of USE buildingblock approach limited # of particles physical units ACCURACY parametrisation based on thermodynamic data multilevel optimisation
drugs patient
mmm!
BOOM
“safety valves” of cell sense tension in the membrane MscL, MscK, MscS, MscM < 10 mN/m
PDB: 2VV5
controllable activation & nonselective conductance
bottom top
flickering conductivity multiple levels subconductive states activation < 1 ms deactivation 1100 ms
Sukharev et al. 1997
Annu Rev Physiol 59: 633657
no ion selectivity even small proteins pass through! 1520 Å
Cruickshank et al. 1997
Biophys J 73: 19251931
attached compound undergoes light induced charge separation reversible localised
Koçer et al. 2005
Science 309: 755758
photosensitive lipids used to transfer signal to mechanical stress reversible localised
Folgering et al. 2004
Langmuir 20: 69856987
aka liposome
aka drugs
tiny lipid vesicles
membrane fusion transmembrane transport drug delivery curvature eects
mechanosensitive
pressure valves of cells touch & hear
nonselective, large membrane channel liposomes MscL
BOOM
660 kN/m·s lysis 140 kN/m·s ok
closed
5 us
67 mN/m 24 nm 1.04 H2O / ns
20 40 60 80 100 120 140 10 20 30 40 50 60 70 80 90 tension pressure
time (µs) tension (mN/m) / pressure (bar) (-0.54 ± 0.02) mN
m /µs
(-1.12 ± 0.05) bar/µs
(86 ± 4) µs (93 ± 4) µs
mimic interactions with bulk solvent
0.5 1 1.5 2 2.5 3 3.5 1 2 3 4 5 6 r [nm]RDF MFFA Risselada et al. 2008
J Phys Chem B 112: 74387447
additional meanfield potential inside the liposome start with r = 0.01 nm increase slowly for 20ns until r = 3.9 nm fill the cavity with water, relax and repeat as needed
modified Lennard Jones potential against water C5 wC5 epsilon 2.0 2.0 sigma 0.47 0.7 DOPC wDOPC
NC3 PO4 GL1 C1 GL2 C2 D3 C4 C5 C1 C2 D3 C4 C5 NC3 PO4 GL1 C1 GL2 C2 D3 C4 C1 C2 D3 C4 C5 wC5
V (r) = 4ǫ σ r 12 − σ r 6
C5 wC5 NC3 PO4 GL1 C1 GL2 C2 D3 C4 C5 C1 C2 D3 C4 C5
divide system into a 3D grid use local virial for each volume element calculate averages
Plocal(r) = 1 V
i
δ (r − ri) mivi ⊗ vi + 1 2
Fij
δ(r − 1)dl
Ollila et al. 2009 Phys Rev Lett, 102: 078101
R
5 10 15 20 Box (nm) 500 1000 1500 2000 Density (kg m
Protein wDOPC W PO4
Partial densities
R
largescale biological systems accessible to CG simulations release of an osmotic shock via MscL activation achieved MscL activation is indeed a lastditch eort to prevent lysis irislike, nonsymmetric
water flux OUT: 6.0 ± 1.3
ions/ns
IN: 1.7 ± 0.3
ions/ns
MODEL: 0.240 ions/ns
pore radius 11.6 ± 0.8 Å
blocking of the channel by the cytoplasmic helices a first step in closure?
dye molecules to directly compare our release of nanoparticles to experimental data activation of the channel using lysolipids nanopores formed by
antimicrobial peptides
SiewertJan Marrink Erik van der Giessen Jelger Risselada
UPPSALA UNIVERSITET TAMPERE UNIVERSITY OF TECHNOLOGY
David van der Spoel Samuli Ollila Ilpo V attulainen
Stockholm University
Erik Lindahl