Study of the mechanism of action of lineal bacteriocins using suicide probes

BELLOMIO A; RIOS COLOMBO NS; BARRAZA D; GALVAN AE; ACUÑA L; LANZA L; NAVARRO S; MINAHK C; CHALON MC

Paraná

Congreso; LIV Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2018

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Most of the antimicrobial peptides produced by bacteria, called bacteriocins, have a spectrum of action limited to bacteria phylogenetically related to the producing strain. They generally act at the cell membrane of target bacteriadissipating the transmembrane electrical potential by forming pores. In our laboratory, we study its mechanism of action and develop new bacteriocins with expanded spectrum of action. In recent years, it was found that the specificity of many bacteriocins is because they require a specific protein receptor in the cell membrane. To better understand which role the receptor plays in the mechanism of action of some linear bacteriocins, we built suicide probes. To construct the suicide probes, the etpM gene portion, which codes for the transmembrane helix of the EtpMbitopic protein, was fused with the structural gene of different lineal bacteriocins. These fusions were cloned under the control of the PBAD promoter in E. coli. When the suicide probes are expressed by adding arabinose to the culture medium, the transmembrane potential dissipation occurs and the bacterium dies, even in the absence of the membrane receptor. The co-expression of the bacteriocin-specific immunity protein prevents the dissipation of the transmembrane potential and the cells remain viable. The results presented in this work agree with the hypothesis that one of the roles of the receptor protein would be to anchor the bacteriocins in the membrane so that they can penetrate the lipid bilayer and form the pore.