Inhibition of metallo-beta-lactamase by RNA

This work describes the discovery and characterization of various RNA oligomers that act as metallo-â-lactamase inhibitors. Screening of Bacillus cereus metallo-â-lactamase using RNA generated by SELEX identified a 30-mer RNA, an U-mer RNA, and an undefined random pool of RNA with inhibitory activity against B. cereus metallo-â-lactamase.

The 30-mer RNA is a noncompetitive inhibitor with an IC50 value of 11 nM. The Ki and Ki' values are 2 and 15 nM, respectively. The 30-mer RNA shows no effect on the activity of the B. cereus 569/H/9 â-lactamase I or bovine carboxypeptidase A indicating that the inhibition is highly specific for the metallo-â-lactamase.

The 11-mer RNA is a loop-region of the 30-mer RNA that was synthesized to test for inhibition. The IC50 value of the 11-mer RNA is 430 nM. No further testing was conducted on the 11-mer RNA as the inhibition was reduced.

A pool of RNA before any selection was tested for inhibition; the IC50 value of the random pool of RNA is 21 pM. In the future, further testings will be conducted with the random pool to identify more effective RNA inhibitor(s).

Utilizing SELEX was successful in identifying RNA-based inhibitors of metallo-â-lactamase. Upon modifications of the oligonucleotides, this may lead to a new generation of highly efficient and specific aptamer inhibitors of metallo- â-lactamase.