Differential Chromosome- and Plasmid-Borne Resistance of <i>Escherichia coli hfq</i> Mutants to High Concentrations of Various Antibiotics
The Hfq protein is a bacterial RNA chaperone, involved in many molecular interactions, including control of actions of various small RNA regulatory molecules. We found that the presence of Hfq was required for survival of plasmid-containing <i>Escherichia coli</i> cells against high conc...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-08-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/22/16/8886 |
| Summary: | The Hfq protein is a bacterial RNA chaperone, involved in many molecular interactions, including control of actions of various small RNA regulatory molecules. We found that the presence of Hfq was required for survival of plasmid-containing <i>Escherichia coli</i> cells against high concentrations of chloramphenicol (plasmid p27cmr), tetracycline (pSC101, pBR322) and ampicillin (pBR322), as <i>hfq</i><sup>+</sup> strains were more resistant to these antibiotics than the <i>hfq</i>-null mutant. In striking contrast, production of Hfq resulted in low resistance to high concentrations of kanamycin when the antibiotic-resistance marker was chromosome-borne, with deletion of <i>hfq</i> resulting in increasing bacterial survival. These results were observed both in solid and liquid medium, suggesting that antibiotic resistance is an intrinsic feature of these strains rather than a consequence of adaptation. Despite its major role as RNA chaperone, which also affects mRNA stability, Hfq was not found to significantly affect <i>kan</i> and <i>tet</i> mRNAs turnover. Nevertheless, <i>kan</i> mRNA steady-state levels were higher in the <i>hfq</i>-null mutant compared to the <i>hfq</i><sup>+</sup> strain, suggesting that Hfq can act as a repressor of <i>kan</i> expression.This observation does correlate with the enhanced resistance to high levels of kanamycin observed in the <i>hfq</i>-null mutant. Furthermore, dependency on Hfq for resistance to high doses of tetracycline was found to depend on plasmid copy number, which was only observed when the resistance marker was expressed from a low copy plasmid (pSC101) but not from a medium copy plasmid (pBR322). This suggests that Hfq may influence survival against high doses of antibiotics through mechanisms that remain to be determined. Studies with pBR322Δ<i>rom</i> may also suggest an interplay between Hfq and Rom in the regulation of ColE1-like plasmid replication. Results of experiments with a mutant devoid of the part of the <i>hfq</i> gene coding for the <i>C</i>-terminal region of Hfq suggested that this region, as well as the <i>N</i>-terminal region, may be involved in the regulation of expression of antibiotic resistance in <i>E. coli</i> independently. |
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| ISSN: | 1661-6596 1422-0067 |