SOCIAS Sergio Benjamin
Ile13 residue of microcin J25 is essential for recognition by the receptor FhuA but not by the inner membrane transporter SbmA
SOCÍAS, S. B., SEVERINOV, K. SALOMÓN, R. A.
FEMS MICROBIOLOGY LETTERS
WILEY-BLACKWELL PUBLISHING, INC
Lugar: Reading, UK; Año: 2009 vol. 301 p. 124 - 129
Abstract Entry of the peptide antibiotic microcin J25 in target cells is mediated by the outer membrane receptor FhuA and the inner membrane protein SbmA. The latter also transports microcin B17 into the cell cytoplasm. Comparison of microcin J25 and B17 revealed a tetrapeptide sequence (VGIG) common to both antibiotics. We speculate that this structural feature in microcin J25 could be a motif recognized by SbmA. To test this hypothesis, we used a microcin J25 variant in which the isoleucine in VGIG (position 13 in microcin J25 sequence) was replaced by lysine (I13K). In experiments in which the FhuA receptor was bypassed, the substituted microcin showed an inhibitory activity similar to that of wild-type peptide. Moreover, microcin J25 interfered with colin M uptake by FhuA in a competition assay, while the I13K mutant did not. From these results, we propose that the Ile13 residue is required only for interaction with FhuA, and that VGIG is not a major recognition element by SbmA