INVESTIGADORES
CHALON Miriam Carolina
congresos y reuniones científicas
Título:
In vivo systems to study class II bacteriocins toxicity and immunity
Autor/es:
RIOS COLOMBO, N.S.; CHALON M.C.; GALVÁN, A.E.; NAVARRO, S.A; LANZA, L; BARRAZA D; ACUÑA L; FERNANDEZ DE ULLIVARRI, M.; MINAHK, C.J; BELLOMIO, A
Lugar:
La Plata, Buenos Aires
Reunión:
Congreso; XLVII Reunion Anual de la Sociedad Argentina de Biofisica; 2018
Institución organizadora:
Sociedad Argentina de Biofisica
Resumen:
Class II bacteriocins are membrane-active peptides that act over a narrowspectrum of bacterial targets and have a great potential application as antibioticsin medical sciences. They act on the cytoplasmic membrane dissipating thetransmembrane potential by forming pores. There is solid evidence thatmembrane receptor proteins are necessary for their function, however the preciserole of this receptor and the nature of the pore remain elusive. The most acceptedmodel suggest that bacteriocins bind the receptor to change its conformation,creating a channel that remains open. Nonetheless, several studies support asecond model in which the bacteriocin is able to disrupt the membrane itself andthe receptor might act just as an anchor allowing the subsequent bacteriocininsertion to form the pore. In order to reveal whether or not the pore structureinvolves the specific receptor, we designed chimeric peptides fusing themembrane protein EtpM with different class II bacteriocins. We chose E. coli as a receptor-free expression host. The fusion EtpM-bacteriocin anchors eachbacteriocin to the membrane and kills the expressing host cell, even in theabsence of the specific receptor. These results are in line with the second model in which the pore is formed through a receptor-independent interaction with the lipid bilayer. The effect of these interactions was also analyzed, through a fluorophore that changes its fluorescence intensity according to transmembrane potential. On the other hand, an immunity protein protects the producer strain against its own bacteriocin. For antimicrobials under investigation for clinical applications, the potential emergence of resistant pathogens and the study of immune mechanisms are a primary concern. Though no direct in vitro interaction bacteriocin-immunity has been reported before, by using an in vivo system, we present evidence that this binding might occur, not in aqueous solution but in a membrane inserted conformation