INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of fatty acylation on the interaction of E. coli alpha hemolysin with lipid Langmuir monolayers
Autor/es:
PAVINATTO, F.; OLIVEIRA, O.; DAZA MILLONE, M. A.; BAKÁS, L.; MATÉ, S.; VÁZQUEZ, R.; HERLAX, V.; VELA, M. E.
Lugar:
San Miguel de Tucuman
Reunión:
Congreso; Latin American Federation of Biophysical Societies (LAFeBS) / IX IberoAmerican Congress of Biophysics / XLV Reunión Anual SAB 2016; 2016
Resumen:
Alpha-hemolysin (HlyA) is considered the prototype member of the RTX toxin family of Gram negative bacteria and constitutes the main virulence factor produced by uropathogenic E. coli strains. This protein toxin is synthetized as a protoxin (ProHlyA) that is transformed into the active form in the bacterial cytosol prior to its secretion. The posttranslational modification consists in the amide-linkage of fatty-acyl moieties to the ε-amino groups of two internal lysine residues. HlyA and ProHlyA bind to the same extent to erythrocyte membranes but only HlyA produces cell lysis. In a very recent study, however, we have demonstrated that ProHlyA still induces early morphologic shape transitions in rabbit erythrocytes1. In the present work, with the aim at further studying the effect of fatty acylation on protein-membrane interactions, we explored the association of the acylated and unacylated forms of HlyA with lipid monolayers mimicking the outer leaflet of red blood cell membranes. Surface pressure measurements were performed that evidenced a faster incorporation of the acylated protein into the lipid films. Polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS) measurements revealed that the adsorption of the proteins to the lipid monolayers produced an increase in the lipid acyl chains disorder independently of protein-fatty acylation. When pure proteins films were analyzed by PM-IRRAS, different secondary structure elements were found exposed at the air-water interface, being the entire HlyA polypeptide chain more extended than its unacylated counterpart. These differences in protein arrangement at a hydrophobic-hydrophilic interface could be an important factor for biological activity.[1] Vázquez, R.F., et al. Biochim Biophys Acta 1858 (8): 1944-53, 2016.Acknowledgments: This work was supported by grants from UNLP, ANPCyT and CIC-PBA.