The role of respiratory oxidases in the mechanism of action of Microcin J25

SCHURIG-BRICCIO, LICCI; BELLOMIO, AUGUSTO; CHALÓN, MIRIAM CAROLINA; GENNIS, ROBERT; GALVÁN, ADRIANA EMILCE; MINAHK, CARLOS JAVIER

Córdoba

Congreso; LII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2016

The antibacterial peptide microcin J25 (MccJ25) displays an antibiotic activity against Salmonella, Shigella and Escherichia coli. MccJ25 has two cellular targets, the RNA polymerase and the respiratory chain. The terminal oxido-reductases in E. coli respiratory system are the cytochromes bo3 and bd. We studied the effect of MccJ25 in E. coli C43 cytochrome mutant strains. The oxygen consumption was diminished by MccJ25 in the wild type strain and in the mutant strain lacking the cytochrome bo3, but did not have any effect in ∆bdI strain. In the same way, superoxide production in isolated membranes was increased more than 100 % in the control and ∆bo3 strain, whereas in cytochrome bd mutant such increment was not observed. Moreover, working with purified cytochromes, MccJ25 inhibited about 25 % the ubiquinol oxidase activity only on cytochrome bdI, while under identical experimental conditions bo3 oxidase was insensitive to the peptide. These results demonstrate that cytochrome bdI plays an important role in the microcin J25 mechanism of action on the respiratory chain of E. coli. Our findings would provide a new insight into the application of MccJ25 in food or pharmaceutical industries.