Investigating Riboswitches in Enterobacteria as Potential Antimicrobial Drug Targets

• Published in: Asia-Pacific journal of molecular biology and biotechnology Vol. 30; p. 97
• Main Authors: Shahid, Umama, Tan, Hock Siew
• Format: Journal Article
• Language: English
• Published: Kuala Lumpur Malaysian Society for Molecular Biology and Biotechnology 01-06-2022
• Subjects: 5' Untranslated Regions; Antibiotic tolerance; Antibiotics; Antimicrobial agents; Antimicrobial resistance; Biosynthesis; Cellular stress response; Gene expression; Klebsiella; Ligands; Metabolites; Microorganisms; Minimum inhibitory concentration; Multidrug resistance; Next-generation sequencing; Nucleic acids; Pathogenicity; Pathogens; Riboswitches; Strains (organisms); Therapeutic targets; Virulence
• ISSN: 0128-7451

Introduction: Drug overuse and evolution of microorganisms has made antimicrobial resistance one of the most critical threats currently. Pathogens, like the ESKAPE group, have become resistant to most of the commercial antibiotics. This calls for an urgent increase in available repertoire of targets for antimicrobial agents. Until recently, only proteins were considered druggable targets and this potential of nucleic acids remained largely underexplored. We focus on riboswitches, a class of regulatory RNAs, as prospective antimicrobial drug targets. Riboswitches are short stretches in 5'UTR of mRNA that can specifically bind to small ligands and regulate gene expression. They are known to control virulence, antibiotic tolerance, and biosynthesis of essential metabolites in bacteria. Our aim is to screen the antibiotic-responsive riboswitches in Enterobacteriaceae and target them to reverse multidrug resistance in pathogens. Methods: Three Klebsiella pneumoniae strains were compared based on their susceptibilities to 9 antibiotics belonging to 5 different classes and pathogenicity in Caenorhabditis elegans. Results: ATCC BAA-1705 was highly resistant to all the antibiotics tested but was comparatively less pathogenic than ATCC10031, which interestingly was exceptionally susceptible to the tested drugs. Conclusion: These contrasting strains were shortlisted for further screening using a high throughput sequencing technique, term-seq. Next, optimal ligand concentration and induction time are being identified by cultivating the strains under stress at sub-lethal concentrations (0.9x MIC, 0.5x MIC, 0.25x MIC and 0.1x MIC) and by quantifying the expression of stress response genes, at various timepoints. Candidate riboswitches will then be validated using molecular assays.