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Cytochrome c biogenesis is involved in the transposon Tn 5 ‐mediated bleomycin resistance and the associated fitness effect in Escherichia coli
Author(s) -
Adam Eric,
Volkert Michael R.,
Blot Michel
Publication year - 1998
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1998.00755.x
Subject(s) - biology , transposable element , biogenesis , escherichia coli , genetics , cytochrome , cytochrome c , microbiology and biotechnology , mutant , gene , biochemistry , apoptosis , enzyme
The transposon Tn 5 ble gene and the Escherichia coli alkylation‐inducible aidC locus are co‐operatively involved in the resistance to the anti‐cancer drug and DNA‐cleaving agent bleomycin and enhance fitness of bacteria in the absence of the drug. In this report, we demonstrate that the aidC locus is identical to nrfG the last gene of the nrf operon involved in the periplasmic formate‐dependent nitrite reduction. In the presence of Ble, NrfG expression is specifically induced and restores both bleomycin resistance and its associated beneficial growth effect in an aidC − strain. In vitro DNA protection assays reveal that purified Ble prevents bleomycin‐mediated DNA breakage, as do bleomycin‐binding proteins. Similarities between haems of the cytochrome c biogenesis nrf pathway and iron bleomycin suggest a DNA repair‐independent molecular mechanism for both bleomycin resistance and increased viability. The Ble protein binds bleomycin and prevents DNA breakage. It also induces the nrf locus that may assimilate bleomycin into haem for extracellular transport or inactivate bleomycin. Inactivation of potent DNA oxidants confers a better fitness to the bacterium carrying the transposon, suggesting a symbiotic relationship between host and transposon.