Inhibition of β-lactamase I from Bacillus cereus by ssDNA.

Abstract

Inhibitors of β-lactamases are important to the treatment of infectious diseases when used in conjunction with a β-lactam antibiotic. Current inhibitors of β-lactamase such as clavulanic acid, sulbactam, and tazobactam perform efficiently overall but due to developing bacterial resistances to these inhibitors, new inhibitors need to be discovered. SELEX procedures were used to isolate ssDNA aptamers capable of binding to the enzyme active site and consequently inhibit the action of β-lactamase I from Bacillus cereus 569/H/9. A 22 base ssDNA aptamer was discovered to have an inhibition pattern consistent with reversible competitive inhibition. These results prompted further study of a hairpin loop of 10 bases and a linear 11 base ssDNA aptamer which were truncated forms of the original 22 base aptamer. The 11 base aptamer failed to show any inhibition against β-lactamase I, whereas the 10 base aptamer showed competitive reversible inhibition.