Reconstitution and physical studies of a bacteria nano-pump
Bacteria control their intracellular concentration of various substrates
(antibiotics, heavy metals) by organizing their expulsion through
efflux pumps the mechanism of which is unknown. These pumps,
inserted into the bacterial membrane, can induce bacterial resistance to
antibiotics. Understanding how they work would determine the way to
block them and thus reduce the bacterial resistance. For gram-negative
bacteria, these pumps are usually made of three parts: one in the outer
membrane, another one in the inner membrane, and a third one located
between the two membranes of the bacteria. The project aims to
reconstitute a specific pump as a whole, within an artificial double
bilayer system in order to study its function. We have previously
shown that the model system is biologically relevant by measuring the
activities of several trans-membrane proteins in an identical system.
The production of all the three components of the pump is now under
control. We first want to perform measurements on individual links
between the different pump components to understand the stability of
the whole pump. Afterwards the pump will be reconstituted in vitro by
inserting the different pump components into the lipid membranes of
vesicles. The study of its function will be performed by observing the
crossing of fluorescent molecules from one vesicle to another.
Relevant Publications:--------------------------------------------Gambin, Y; Reffay, M; Sierecki, E; Homblé, F; Hodges, R.; Gov N; Taulier,
N; Urbach, W
"Variation of the Lateral Mobility of Transmembrane Peptides with
Hydrophobic Mismatch"
J.Phys. Chem.B. 114, 3559–3566 (2010)
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Schéma des trois éléments de la
nanopompe biologique (pompe à efflux).
- Le "tuyau" traversant la membrane
externe (OM) en orange.
- Le transporteur (bleu) inséré dans la
membrane interne et l'adaptateur
periplasmique (vert) accroché à la
membrane interne par des acides gras (zigzag).
- L'adaptateur relie le tuyau externe et la
partie active de la pompe Son rôle reste mal
défini.
- Les points rouges indiquent les principes
actifs antibactériens expulsés par la pompe
(flèche).
D'après Symmons et al PNAS 2009
M. Reffay, Y. Gambin, H. Benabdelhak, G. Phan, N. Taulier, A. Ducruix, R.S. Hodges, W. Urbach
"Tracking membrane protein association in model membranes."
PLoS ONE Avril 2009
Maldonado A, Ober R, Gulik-Krzywicki T, Urbach W. and .Langevin D.
The sponge phase of a mixed surfactant system
Journal of Colloid and Interface Science, 308 (2): 485-490 2007
Kurtisovski E, Taulier N, Ober R, M. Waks and W Urbach
Molecular origin of model membrane bending rigidity
Physical Review Letters, 98 (25): 2007
Y. Gambin, R. Lopez-Esparza, M. Reffay, E. Sierecki, N. S. Gov, R. S.Hodges, and W. Urbach.
Lateral mobility of proteins in liquid membranes revisited.
PNAS, 103(7):2098-2102, 2006
S. Abel, M. Waks, W. Urbach, and M. Marchi.
Structure, stability, and hydration of a polypeptide in AOT reverse micelles.
Journal of the American Chemical Society, 128(2):382-383, 2006
Y. Gambin, G. Massiera, L. Ramos, C. Ligoure, and W. Urbach.
Bounded step superdiffusion in an oriented hexagonal phase.
Physical Review Letters, 94(11), 2005.