Department of Biology, University of the Balearic Islands
Università degli Studi di Salerno Dottorato di Ricerca in Scienza e Tecnologie per l’Industria Chimica, Farmaceutica e Alimentare XI CICLO Studio di interazione di molecole attive su membrane cellulari mediante tecniche bioinformatiche e di dinamica molecolare
Analysis: binding energy “ Effect of g protein lipids on membrane structure and g protein-membrane interactions” Jesús Casas 1 , Rafael Álvarez 1 , Silvia Terés 1 , Victoria Lladó 1 , Federica Campana 2 , Stefano P. Piotto 2 , and Pablo V. Escribá 1 1 Laboratory of Molecular Cell Biomedicine, Department of Biology, IUNICS, University of the Balearic Islands, E-07122 Palma de Mallorca, Spain. 2 Department of Pharmaceutical Sciences, University of Salerno, Via Ponte don Melillo, 84084 Fisciano (SA), Italy Submitted to the Biochemical Journal.
MA and PA interact strongly with PC membranes than GG.
The addition of GG decreases drastically the lateral pressure of POPC membranes than other fatty acids: this is possibly due to the greater volume of the isoprenoid and the tight packing of the GG-free PC membrane.
GG increases markedly the non-lamellar phase propensity.
G βγ and G αβγ prefer non-lamellar prone regions and G α lamellar membranes.
The regulatory effect of GG on the membrane may explain its influence on the binding of G proteins.
Two asymmetric membranes made of sphingomyelin (SM) and cholesterol (CHOL) with BGP-15 at different pH values or without BGP-15 (control).
Inner leaflet composition:
Outer leaflet composition:
P= 1 atm.
Force field = AMBER03.
Cutoff = 7.86 Å.
Time step = 1.25 fs for intramolecular forces and 2.5 fs for intermolecular forces
Simulation time = 5ns
Density profile (1): Density profiles permit easily to monitor the position of any molecule during the simulation. In the figure are shown the density distribution of water (cyan line), cholesterol (green) and sphingomyelin OSF (blue).
Density profile (2): In the figures are shown the initial densities distribution (on the left) and the situation after 5 ns (on the right). Since the bilayer was not symmetric, one can observe that BGP-15 tends to be preferentially absorbed where the ratio SM-CHOL is close to one (on the right of the diagram). (a) (b)
Density profile (3): Density distribution for 12 atom types at t=0 (a) and after 5ns (b). The uptake of BGP-15 induce a swelling and an increase of disorder in the terminal carbons. (a) (b)
Order parameter: BGP-15 enter the membrane without penetrating in the hydrophic core. The presence of BGP-15 among the SM headgroups increases the ordering. BGP-15 do not alter the internal organization of cholesterol and do not significantly alter the pressure profile.