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

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

Córdoba

Congreso; LII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2016

SAIB

p { margin-bottom: 0.25cm; line-height: 120%; }a:link { }The antibacterialpeptide microcin J25 (MccJ25) displays an antibiotic activity againstSalmonella, Shigella and Escherichia coli. MccJ25 has two cellulartargets, the RNA polymerase and the respiratory chain. The terminaloxido-reductases inE. coli respiratory system are the cytochromes bo3and bd. We studied the effect of MccJ25 in E. coli C43 cytochromemutant strains. The oxygen consumption was diminished by MccJ25 inthe wild type strain and in the mutant strain lacking the cytochromebo3, but did not have any effect in ΔbdI strain. In the same way,superoxide production in isolated membranes was increased more than100 % in the control and Δbo3 strain, whereas in cytochrome bdmutant such increment was not observed. Moreover, working withpurified cytochromes, MccJ25 inhibited about 25 % the ubiquinoloxidase activity only on cytochrome bdI, while under identicalexperimental conditions bo3 oxidase was insensitive to the peptide.These results demonstrate that cytochrome bdI plays an important rolein the microcin J25 mechanism of action on the respiratory chain ofE. coli. Our findings would provide a new insight into theapplication of MccJ25 in food or pharmaceutical industries.