INVESTIGADORES
BELLOMIO Augusto
congresos y reuniones científicas
Título:
Microcin J25 induces ATP depletion in Escherichia coli cells
Autor/es:
CHALÓN MC; BELLOMIO A; FARIAS RN; SALOMON RA; VINCENT PA
Lugar:
Rosario, Santa Fe. Argentina
Reunión:
Congreso; XLII Reunión Anual SAIB; 2006
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular
Resumen:
After
entering sensitive cells through the outer membrane receptor FhuA, the
21-residue peptide antibiotic microcin J25 (MccJ25) displays a dual mechanism
of action: it inhibits both RNA polymerase (RNAP) and cell respiration. The
latter effect is apparently mediated by an overproduction of superoxide radical
which, in turn, would affect superoxide-sensitive enzymes from the respiratory
chain, leading to a reduction in the intracellular levels of ATP. In the
present work, we examined the effect of MccJ25 on E. coli ATP levels using a
luciferin-luciferase bioluminescence method. Our results show that MccJ25
induces a significant ATP reduction in the MccJ25-hypersensitive strain AB1133,
whereas no effect was detected by using strain MC4100, which has an intrinsic
partial resistance to the antibiotic. A drop in ATP levels took place also in
PA232 (pGC01), a strain that carries a mutated MccJ25-resistant RNAP and
overexpress the FhuA receptor (encoded by plasmid pGC01). Previously, we
observed that the increase in superoxide radical production caused by MccJ25
was prevented by the addition of the enzyme superoxide dismutase (SOD). Since
only a small ATP depletion occurred when cells were coincubated with MccJ25 and
SOD, we conclude that the fall in ATP levels is a consequence of superoxide
production induced by MccJ25, and that this effect is independent of RNAP inhibition.