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

Abstract

Hydrolysis of β-lactam antibiotics by β-lactamase enzymes is the most common mechanism of bacterial resistance to these agents. Several small-molecule, mechanism-based inhibitors of β-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 β-lactamases. Here we utilized phage display to identify peptides that bind to the class A β-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 β-lactamase with a Ki of 136 μM. Surprisingly, the peptide inhibits the class A Bacillus anthracis Bla1 β-lactamase with a K i of 42 μM and the class C β-lactamase, P99, with a K i of 140 μM, 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-β-lactam, broad-spectrum peptidomimetic inhibitors of β-lactamases.