release of content through mechano- sensitive gates …€¦ · sukharev et al.!1997" annu rev...
TRANSCRIPT
RELEASE OF CONTENT THROUGH MECHANO-
SENSITIVE GATES IN PRESSURISED LIPOSOMES
Martti LouhivuoriUniversity of Groningen
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
MARTINI
coarse-grained model
www.cgmartini.nl
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
MARTINI CG modelinteraction sites
DPPC cholesterol peptide !ALYWK"
water
butane
C1
SC1
SC3
SP1QaQo
Na
C1
SC4
P4
C1
C5
SNd
SC4
SC4
Qd
SP1
C3No
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
parametrisation of MARTINI
experimental !thermodynamic" data
! non#bonded interactions
atomistic MD simulations
! bonded interactions
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
parametrisationbonded interactions
angle
dist
ribu
tion
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
parametrisationnon#bonded interactionsM. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
Rhombohedral phase (experimentally observed for DOPC/DOPE 3:1 and 2:1 Lyan & Huang, 2002)
side view top view
THE VALIDATIONTHE VALIDATION comparing to experimental measurements
Reproduced in CG simulation (Marrink & Mark, Biophys. J., 2004)
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
bilayers rafts
sugars
membrane proteins
vesicles
vesicles w/ proteins
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
bilayers rafts
sugars
membrane proteins
vesicles
vesicles w/ proteins
MARTINI CG modelinteraction sites
DPPC cholesterol peptide !ALYWK"
water
butane
C1
SC1
SC3
SP1QaQo
Na
C1
SC4
P4
C1
C5
SNd
SC4
SC4
Qd
SP1
C3No
SPEEDshort#range interactions
large time#stepfew degrees of freedom
GENERALconsistent modeling
biomolecular systemseasily extended
EASE of USEbuilding#block approach
limited # of particlesphysical units
ACCURACYparametrisation based on
thermodynamic datamulti#level optimisation
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
drugs patient
targeted drug release.how?
mmm!ouch!
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
drug delivery vehicle“nanobot”
BOOM
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
drug delivery vehicle“nanobot”
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
mechano-sensitive channels
“safety valves” of cell
sense tension in the membrane
MscL, MscK, MscS, MscM
< 10 mN/m
PDB: 2VV5
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
MscLcontrollable activation & non!selective conductance
bottom
top
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
MscL activity
flickering conductivity
multiple levels
! subconductive states
activation < 1 ms
de#activation 1$100 msSukharev et al. !1997"
Annu Rev Physiol 59: 633$657
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
non-selective channel
no ion selectivity
even small proteins pass through! 15$20 Å
Cruickshank et al. !1997"Biophys J 73: 1925$1931
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
photosensitivivity
attached compound undergoes light induced charge separation
reversible
localised Koçer et al. !2005"Science 309: 755$758
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
photosensitivivity
photosensitive lipids used to transfer signal to mechanical stress
reversible
localised
Folgering et al. !2004"Langmuir 20: 6985$6987
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
nano-containeraka liposome
nano-particlesaka drugs
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
nano-transporter
tiny lipid vesiclesmembrane fusion
trans#membrane transport
drug delivery
curvature e%ects
mechano#sensitivepressure valves of cells
touch & hear
non#selective, large membrane channel
liposomes
MscL
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
game plan
BOOM
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
MscL saves the day
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
oh-oh! 660 kN/m·s ! lysis
140 kN/m·s ! ok
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
analysis
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
analysisclosed open 5 us
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
activation
mechanism
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
post-activation
67 mN/m
" 24 nm
1.04 H2O / ns
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
equilibrium?
0
20
40
60
80
100
120
140
0 10 20 30 40 50 60 70 80 90
tensionpressure
time (µs)
tensi
on
(mN
/m
)/
pre
ssure
(bar
)
(-0.54 ± 0.02) mNm
/µs
(-1.12 ± 0.05) bar/µs
(86 ± 4) µs
(93 ± 4) µs
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
-30
-20
-10
0
10
20
30
2 3 4 5 6
r [nm]
MFFA boundary potentials
mimic interactions with bulk solvent
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5 6
r [nm]
RDF
MFFA
Risselada et al. !2008"J Phys Chem B 112: 7438$7447
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
pumping water into liposomes
additional mean#field potential inside the liposome
start with r = 0.01 nm
increase slowly for 20ns until r = 3.9 nm
fill the cavity with water, relax and repeat as needed
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
water-repellant lipid tails
modified Lennard#Jones potential against water
C5 wC5epsilon 2.0 2.0sigma 0.47 0.7
DOPC wDOPC
NC3
PO4
GL1
C1GL2
C2
D3
C4
C5
C1
C2
D3
C4
C5
NC3
PO4
GL1
C1GL2
C2
D3
C4
C1
C2
D3
C4C5wC5
V (r) = 4!!""
r
#12!
""
r
#6$
C5wC5
NC3
PO4
GL1
C1GL2
C2
D3
C4
C5
C1
C2
D3
C4
C5
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
3D pressure fields
divide system into a 3D grid
use local virial for each volume element
calculate averages
Plocal(r) =1V
!
"#
i
! (r ! ri)mivi " vi +12
#
i !=j
Fij
$
Cij!(r ! 1)dl
%
&
Ollila et al. !2009"Phys Rev Lett, 102: 078101
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
flow rate
R
0 5 10 15 20Box (nm)
0
500
1000
1500
2000
Den
sity
(k
g m
-3)
ProteinwDOPCWPO4
Partial densities
R
!
!
summarylarge#scale biological systems accessible to CG simulations
release of an osmotic shock via MscL activation achieved
MscL activation is indeed a last#ditch e%ort to prevent lysis
iris#like, non#symmetric opening
water flux OUT: !6.0 ± 1.3"& ions/ns
IN: !1.7 ± 0.3"& ions/ns
MODEL: 0.2$40& ions/ns& Steinbacher et al. !2007" & CurrTopicsMembranes 58:1#24
pore radius !11.6 ± 0.8" Å& !exp. 15$20 Å"
blocking of the channel by the cytoplasmic helices a first step in closure?
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
future
dye molecules to directly compare our release of nano#particles to experimental data
activation of the channel using lyso#lipids
nano#pores formed by other molecules, e.g. anti#microbial peptides
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
M. Louhivuori / ISSP workshop / Tokyo, 24.8.2010
Siewert#Jan MarrinkErik van der GiessenJelger Risselada
UPPSALA UNIVERSITET
TAMPERE UNIVERSITY OF TECHNOLOGY
David van der Spoel
Samuli OllilaIlpo Vattulainen
Stockholm University
Erik Lindahl