Antimitochondrial activity displayed by the antimicrobial peptide microcin J25

In this report we studied the effect of the antimicrobial peptide, microcin J25, on the rat heart mitochondria. This peptide induced an important inhibition of the ATP synthesis with the concomitant enhancement of the ATP degradation. These effects were the result of two processes: on one hand, microcin J25 was able to insert into the membrane and hence alter its permeability with the consequent dissipation of the proton motive force. On the other, microcin J25 inhibited the enzymatic activity of the cytochrome c reductase (complex III) of the respiratory chain. The relevance of this study to the potential use of microcin J25 as an anti-tumoral agent is discussed.