Arginine-containing peptides as potent inhibitors of VIM-2 metallo-β-lactamase

Background: Metallo-beta-lactamases (MBLs) play an important role in the emergence of microbial resistance to beta-lactam antibiotics, and are hence considered targets for the design of novel therapeutics. We here report on the inhibitory effect of peptides containing multiple arginine residues on VIM-2, a clinically important MBL from Pseudomonas aeruginosa. Methods: Enzyme kinetic assays in combination with fluorescence spectroscopy and stopped-flow UV-Vis spectrophotometry were utilized to explore the structure-activity relationship of peptides as inhibitors of VIM-2. Results: Our studies show that the inhibitory potency of the investigated peptides was mainly dependent on the number of arginine residues in the center of the peptide sequence, and on the composition of the N-terminus. The most potent inhibitors were found to curtail enzyme function in the mid-to-low nanomolar range. Salts generally reduced peptide-mediated inhibition. Analysis of the mode of inhibition suggests the peptides to act as mixedtype inhibitors with a higher affinity for the enzyme-substrate complex. Stopped-flow UV-Vis and fluorescence studies revealed the peptides to induce rapid protein aggregation, a phenomenon strongly correlated to the peptides' inhibitory potency. Inhibition of IMP-1 (another subclass B1 MBL) by the peptides was found to be much weaker than that observed with VIM-2, a finding which might be related to subtle molecular differences in the protein surfaces. Conclusion: The reported data indicate that arginine-containing peptides can serve as potent, aggregation-inducing inhibitors of VIM-2, and potentially of other MBLs. General significance: Arginine-containing peptides can be considered as a novel type of potent MBL inhibitors. (C) 2015 Elsevier B.V. All rights reserved.