A broad-spectrum peptide inhibitor of beta-lactamase identified using phage display and peptide arrays

Hydrolysis of beta-lactam antibiotics by beta-lactamase enzymes is the most common mechanism of bacterial resistance to these agents. Several small-molecule, mechanism-based inhibitors of beta-lactamases such as clavulanic acid are clinically available although resistance to these inhibitors has been increasing in bacterial populations. In addition, these inhibitors act only on class A beta-lactamases. Here we utilized phage display to identify peptides that bind to the class A beta-lactamase, TEM-1. The binding affinity of one of these peptides was further optimized by the synthesis of peptide arrays using SPOT synthesis technology. After two rounds of optimization, a linear 6-mer peptide with the sequence RRGHYY was obtained. A soluble version of this peptide was synthesized and found to inhibit TEM-1 beta-lactamase with a K(i) of 136 micro M. Surprisingly, the peptide inhibits the class A Bacillus anthracis Bla1 beta-lactamase with a K(i) of 42 micro M and the class C beta-lactamase, P99, with a K(i) of 140 micro M, despite the fact that it was not optimized to bind these enzymes. This peptide may be a useful starting point for the design of non-beta-lactam, broad-spectrum peptidomimetic inhibitors of beta-lactamases.