Vincent Paula A, Delgado Mónica A, Farías Ricardo N, Salomón Raúl A
Departamento de Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán), Chacabuco 461, 4000 San Miguel de Tucumán, Argentina.
FEMS Microbiol Lett. 2004 Jul 1;236(1):103-7. doi: 10.1016/j.femsle.2004.05.027.
Escherichia coli microcin J25 (MccJ25) is a 2107-Da peptide antibiotic whose uptake into E. coli is mediated by the outer-membrane receptor FhuA and the inner membrane proteins TonB, ExbB, ExbD, and SbmA. A survey of the sensitivity of several Salmonella enterica serovars showed that the antibiotic was highly active against some serovars, while S. Typhimurium, S. Derby, and some S. Enteritidis strains were completely resistant. Resistant strains became hypersensitive to MccJ25 when given the fhuA gene of E. coli, indicating that insensitivity is due to the inability of the FhuA protein to mediate penetration of MccJ25. Whereas in E. coli MccJ25 targets RNA polymerase, in S. Typhimurium it inhibits not only RNA synthesis but also cell respiration. Fluorescence viability staining showed that S. Typhimurium cells exposed to MccJ25 remain viable but are unable to form colonies.
大肠杆菌微菌素J25（MccJ25）是一种2107道尔顿的肽类抗生素，其进入大肠杆菌是由外膜受体FhuA以及内膜蛋白TonB、ExbB、ExbD和SbmA介导的。对几种肠炎沙门氏菌血清型的敏感性调查表明，该抗生素对某些血清型具有高度活性，而鼠伤寒沙门氏菌、德比沙门氏菌和一些肠炎沙门氏菌菌株则完全耐药。当给予大肠杆菌的fhuA基因时，耐药菌株对MccJ25变得高度敏感，这表明不敏感是由于FhuA蛋白无法介导MccJ25的穿透。在大肠杆菌中，MccJ25靶向RNA聚合酶，而在鼠伤寒沙门氏菌中，它不仅抑制RNA合成，还抑制细胞呼吸。荧光活力染色表明，暴露于MccJ25的鼠伤寒沙门氏菌细胞仍具活力，但无法形成菌落。
