Microcin J25 induces ATP depletion in Escherichia coli cells

CHALÓN MC; BELLOMÍO A; FARÍAS RN; SALOMÓN RA; VINCENT PA

Rosario, Santa Fe, Argentina

Congreso; XLII Reunion Anual; 2006

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

Microcin J25 (MccJ25) is a 21- amino-acid antibacterial peptide produced by an enteric Escherichia coli strain. It is active against bacteria Gram (-) like E. coli, Salmonella and Shigella. Entry of microcin in target cells is mediated by the outer membrane receptor FhuA, and the inner membrane proteins TonB, ExbB, ExbD, and SbmA. RNA polymerase is the target of antibiotic action. Other studies demonstrated that MccJ25 inhibits some enzymes of the respiratory chain due to overproduction of especies reactivas del oxygen, this would lead to an ATP depletion. In this work we study the effect of MccJ25 in E. coli ATP levels using a luciferin-luciferase bioluminescence based method. MccJ25 induced an ATP reduction in the more sensitive strain AB1133 but not in MC4100, which has intrinsic MccJ25 resistance. Moreover we determined that ATP decreased also in PA232 (pGC01), a strain whit MccJ25-resistant RNAP and over expressing the outer membrane receptor FhuA. The results obtained suggest that MccJ25 induced ATP reduction on E. coli strains independent on MccJ25 RNAP inhibition. Oxygen in presence of MccJ25 could be reduced producing the radical superoxide. Because of this, we studied the rol of the enzyme superoxide dismutase on the ATP reduction in these strains.