Human Defensines Interactions with Model Bacterial Membranes modelled by Molecular Dynamics Simulations

G. E. BALATTI; M.F. MARTINI; M. PICKHOLZ

Santiago del Estero

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Biofísica.; 2015

SAB

Defensins are a very important group of antimicrobial cationic peptides, and key molecules of the innate immune system. Like others cationic peptides, defensins can interact with negatively charged components of the bacterial membrane, increasing its permeability and thus killing the cell.In order to get insights on the 1-human defensines (1HD) interactions with membranes, we carried out extensive Molecular Dynamics (MD) simulations through a Coarse Grain (CG) model. We use the MARTINI force field1 in combination with the elastic springs network called Elnedyn2 for defensins. Here, we investigate the concentrations effects of 1HD in different model membranes; mainly on 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC, zwitterionic lipid) and 2-oleoyl-1-pamlitoyl-sn-glyecro-3-glycerol (POPG, anionic lipid), presents in eukaryotic and bacterial cells respectively. We also studied the effect of 1HD over glycolipid membranes. Simulations in membranes show that 1HD is essentially found at the lipid water interphase for both, POPC and POPG, lipid bilayers. However, the interaction is most specific with POPG membranes. Simulations are also compared with fully atomistic (small) membranes.Consequently, CG simulations with MARTINI and ElNeDyn can were used to study the effects of cationic peptides on model membranes and to capture the defensine behavior at the molecular level. This is a first step to the understanding of the differential effects of defensines over different probiotic strains, aiming the development of improved probiotic foods.