Targeting TPP Riboswitches Using Chimeric Antisense Oligonucleotide Technology for Antibacterial Drug Development

Nowadays, the emergence and the transmission of multidrug-resistant pathogenic bacteria are a severe menace mounting a lot of pressure on the healthcare systems worldwide. Many severe outbreaks of bacterial infections have been reported worldwide in recent years. Thus, there is an immediate demand to develop antibiotics. Some riboswitches are potential targets for overcoming bacterial resistance. This paper demonstrates the bacteriostatic effect of an antisense oligonucleotide (ASO) engineered to suppress the growth of pathogenic bacteria such as Listeria monocytogenes by targeting the Thiamine Pyrophosphate (TPP) riboswitch. It does not inhibit the growth of the conditional pathogenic bacteria Escherichia coli, as it lacks the TPP riboswitch, showing the specificity of action of our ASO. It is covalently bonded with the cell-penetrating protein pVEC. We did bioinformatics analyses of the thiamine pyrophosphate riboswitch regarding its role in synthesizing the metabolite thiamine pyrophosphate, which is essential for bacteria. L. monocytogenes is intrinsically resistant to cephalosporins and usually is treated with ampicillin. A dosage of ASO has been established that inhibits 80% of bacterial growth at 700 nM (4.5 μg/mL). Thus, the TPP riboswitch is a valuable antibacterial target.