Mutations of bacterial RNA polymerase leading to resistance to microcin J25

Julia Yuzenkova, Monica Delgado, Sergei Nechaev, Dhruti Savalia, Vitaly Epshtein, Irina Artsimovitch, Rachel A. Mooney, Robert Landick, Ricardo N. Farias, Raul Salomon, Konstantin Severinova

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117 Citations (Scopus)


A mutation in the conserved segment of the rpoC gene, which codes for the largest RNA polymerase (RNAP) subunit β′, was found to make Escherichia coli cells resistant to microcin J25 (MccJ25), a bactericidal 21-amino acid peptide active against Gram-negative bacteria (Delgado, M. A., Rintoul, M. R., Farias, R. N., and Salomon, R. A. (2001) J. Bacteriol. 183, 4543-4550). Here, we report that mutant RNAP prepared from MccJ25resistant cells, but not the wild-type RNAP, is resistant to MccJ25 in vitro, thus establishing that RNAP is a true cellular target of MccJ25. We also report the isolation of additional rpoC mutations that lead to MccJ25 resistance in vivo and in vitro. The new mutations affect β′ amino acids in evolutionarily conserved segments G, G′, and F and are exposed into the RNAP secondary channel, a narrow opening that connects the enzyme surface with the catalytic center. We also report that previously known rpoB (RNAP β subunit) mutations that lead to streptolydigin resistance cause resistance to MccJ25. We hypothesize that MccJ25 inhibits transcription by binding in RNAP secondary channel and blocking substrate access to the catalytic center.

Original languageEnglish
Pages (from-to)50867-50875
Number of pages9
JournalJournal of Biological Chemistry
Issue number52
Publication statusPublished - 27 Dec 2002
Externally publishedYes


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