Inhibition of Ampicillin-resistance in Bacteria by Modified DNAzymes

To overcome ampicillin-resistance of bacteria which is believed to attribute their endogenous β-lactamase, we designed three 10-23 DNAzymes(Dz1, Dz2, Dz3) targeting the coding region of β-lactamase mRNA and examined their inhibitory capabilities of the ampicillin-resistance of TEM-1 and TEM-3 bacteria. Dz1 was a traditional 10-23 DNAzyme, Dz2 was the mutant of Dz1 by addition of the protected nucleotide to each arm of the enzyme, and Dz3 was a mutant of Dz1 at antisense arms of which phosphorothioate modifications were made. Kinetic analysis, bacterial growth, and β-lactamase activity measurement showed that all the three DNAzymes worked efficiently in vitro and in vivo. A 9 hours bacterial growth inhibition test showed that the inhibition rates of TEM-1 bacteria by Dz1, Dz2, and Dz3 were 27%, 50%, and 29%, respectively. In addition, the inhibition rates of TEM-3 bacteria by those three DNAzymes were found to be 49%, 58%, and 45%, respectively. The current findings suggest that DNAzymes may become potential candidates of alternative inhibitors for bacteria drug-resistance.