INVESTIGADORES
DELGADO Monica Alejandra
congresos y reuniones científicas
Título:
YojI of Escherichia coli functions as a microcin J25 efflux pump
Autor/es:
DELGADO, MONICA ALEJANDRA; VINCENT, PAULA A.; FARIAS, RICARDO N; SALOMON, RAUL A.; DELGADO, MONICA ALEJANDRA
Lugar:
Misiones
Reunión:
Conferencia; Reunión Anual de SAIB; 2004
Resumen:
YojI OF ESCHERICHIA COLI FUNCIONTS AS A MICROCIN J25 PUMP Delgado M, Vincent PA, Farías RN, Salomón RA. Depto. de Bqca. de la Nutrición. INSIBIO (UNT-CONICET). Inst. de Qca. Biológica-UNT-Tucumán. E-mail: salomon@unt.edu.ar Microcin J25 (MccJ25) is a plasmid-encoded, 21-amino-acid, antibacterial peptide produced by Escherichia coli. In the course of experiments aimed at cloning a MccJ25-resistant mutation, we found a recombinant plasmid able to confer resistance to the antibiotic but, unexpectedly, this plasmid did not contain the mutation. Its analysis led us to the identification of a previously described chromosomal locus, yojI. In the present study, we show that YojI, an Escherichia coli open reading frame of unknown function, mediates resistance to the peptide antibiotic microcina J25 when expressed from a multicopy vector. To see if yojI is functional when present in a single copy, it was necessary to compare the resistance to MccJ25 of wild-type and yojI cells. To this end, the chromosomal yojI gene of strain DH5á was deleted This mutant, in a spot-on-lawn test, was approximately eightfold more sensitive than the control DH5á and showed completely clear zones of growth inhibition. YojI was previously assumed to be an ATP-binding-cassette-type exporter on the basis of sequence similarities. We demonstrate that YojI is indeed capable of pumping out microcin molecules and that it requires the multifunctional outer membrane protein TolC for its function. Thus, one obvious explanation for the protective effect against MccJ25 is that YojI would keep the intracellular concentration of the peptide below a critical level. MccJ25 appears as the first known substrate for YojI.