ROS production induced by microcin J25 is mediated by cytochrome bd

GALVÁN E; CHALÓN MC; SCHURIG-BRICCIO L; MINAHK CJ; GENNIS R; BELLOMIO A

Mar del Plata

Congreso; SAIB LI Reunión Anual; 2015

SAIB

Microcin J25 (MccJ25) is a plasmid-encoded lasso peptide secreted by Escherichia coli that displays antibioticactivity against a range of food-borne Gram-negative pathogens including Escherichia coli, Salmonella and Shigella.The peptide is a potential candidate for a number of applications including food preservation because its resistance toproteolytic degradation and extreme temperatures. The membrane respiratory chain is one of the targets of MccJ25.In fact, this peptide inhibits the oxygen consumption and increases the superoxide production. As a matter of fact,wild type E. coli C43 strain was sensitive to the peptide whereas the ΔbdI ΔbdII double mutant became resistant.Since we had previously demonstrated that MccJ25 inhibited the cytochrome bdI oxidoreductase activity, we decidedto investigate in vitro ROS production with membranes of these mutant strains. The cytochrome bd double mutantmembrane produced the lowest ROS level, indicating a possible role of this oxidoreductase in the MccJ25 mechanismof action. Moreover, we evaluated the sensitivity of different E. coli strains in the presence of the antioxidant ascorbicacid, confirming that the peptide activity was lower when this compound was present.