CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Enhanced sensitivity to pediocin-like peptides in Listeria monocytogenes expressing active prfA master regulator
Autor/es:
JUAN FARIZANO; L. SAAVEDRA; CARLOS MINAHK; ELVIRA MARÍA HEBERT
Reunión:
Simposio; 12th International Symposium on Lactic Acid Bacteria; 2017
Resumen:
The in vitro sensitivity of Listeria monocytogenes to pediocin-like peptides has been evaluated in non-virulent bacteria so far. In the present work, we assess the activity of class IIa bacteriocins in L. monocytogenes cells that constitutively express an activated form of the master virulence regulator PrfA. As expected, these cells displayed a high expression of listeriolysin O and grew poorly in glucose-based minimal medium. Moreover, the physiological glucose transporter, the mannose PTS complex, was downregulated. This complex is also the receptor for pediocin-like bacteriocins, so a reduced sensitivity to these peptides should be expected in cells expressing constitutively activated prfA alleles. However, these cells turned out to be more sensitive to enterocin CRL35 and pediocin PA-1, two class IIa bacteriocins. This result strongly suggests that the expression of the receptor in the plasma membrane of Listeria cells would not be that crucial for activity as it was previously reported. Indeed, other factors should also be taken into account. For instance, we were able to show that membrane lipid composition changed upon expression of the L140F prfA allele. Membranes from virulent cells were significantly more ordered and less compressible than membranes from the parental strain. This highly unanticipated finding may change the current paradigm i.e. the receptor may still be needed for initial docking but membrane lipids emerge as key players in the mechanism of action of these peptides. More importantly, this is the first report on the close relationship between L. monocytogenes virulence and the sensitivity to pediocin-like bacteriocins