The relationship between aminoglycosides' RNA binding proclivity and their antiplasmid effect on an IncB plasmid
Jason R Thomas1, Johna C B DeNap, Margaret L Wong
1Department of Chemistry, Roger Adams Laboratory, University of Illinois, Urbana, Illinois 61801, USA.
Abstract:
Bacteria routinely become resistant to antibiotics through the uptake of plasmids that encode resistance-mediating proteins. Such plasmid-based resistance is seen extensively in clinical settings and has been documented for a wide variety of bacterial infections from both Gram-positive and Gram-negative organisms. We recently reported that a small molecule could be used to mimic a natural process of plasmid elimination, called plasmid incompatibility, and that the addition of this compound causes elimination of an IncB plasmid from E. coli and a subsequent resensitization to antibiotics [DeNap, Thomas, Musk, and Hergenrother (2004) J. Am. Chem. Soc. 126, 15402-15404]. Described herein is a further substantiation and validation of the notion that plasmid incompatibility can be mimicked with small molecules that bind to important RNA targets controlling plasmid replication. In this study, the dissociation constant and stoichiometry of RNA binding are determined for 12 aminoglycosides with stem-loop I (SLI) of the IncB replication machinery. Importantly, it is found that compounds that do not bind to this RNA replication control element fail to induce plasmid loss in vivo, whereas those that do bind to the RNA typically cause measurable plasmid loss. These results highlight the potential for targeting key RNA regions for induction of plasmid loss and the subsequent resensitization of bacteria to antibiotics.
Insights
Small molecules can mimic plasmid incompatibility to eliminate antibiotic resistance plasmids from bacteria. This approach resensitizes bacteria to antibiotics by targeting key RNA replication control elements.
Area of Science:
- Microbiology
- Molecular Biology
- Drug Discovery
Background:
- Antibiotic resistance is a major clinical challenge, often mediated by plasmids.
- Plasmid incompatibility is a natural mechanism for plasmid elimination in bacteria.
Purpose of the Study:
- To validate and substantiate the use of small molecules to mimic plasmid incompatibility.
- To investigate the potential of targeting RNA replication control elements for plasmid elimination.
Main Methods:
- Determined dissociation constants and stoichiometry of aminoglycoside binding to IncB plasmid stem-loop I (SLI) RNA.
- Assessed the ability of small molecules to induce plasmid loss in vivo.
- Correlated RNA binding with plasmid elimination efficacy.
Main Results:
- 12 aminoglycosides were characterized for their binding to SLI RNA.
- Compounds binding to SLI RNA induced measurable plasmid loss in vivo.
- Compounds not binding to SLI RNA failed to induce plasmid loss.
Conclusions:
- Small molecules can effectively mimic plasmid incompatibility by targeting essential RNA replication elements.
- Targeting RNA replication control offers a promising strategy for inducing plasmid loss.
- This approach can lead to the resensitization of bacteria to antibiotics.
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