Combined Screening of Different beta-lactamases Enzymes and CipP Protease from Staphylococcus aureus to identify Pharmaceutical Hits

Abstract

Bacteria has evolved in much more rigorous conditions that today; they have developed mechanisms to survive. A need is for novel antibiotics is imperative. Beta-lactamases are enzymes produced by bacteria that provide multi-resistance to beta-lactam antibiotics. Beta-lactamase provides antibiotic resistance by changing the antibiotics\u27 structure. We are also investigating a protease ClpP that is in S. aureus maintaining protein homeostasis. Here, we describe the use of an iterative in silico and in vitro workflow for identifying novel beta-lactamase and protease ClpP inhibitors. Utilizing Molecular Operating Environment (MOE) as the software for our virtual screens. Our virtual screen model evaluates compounds that can be purchased for less than one- hundred dollars, therefore they can eventually be evaluated in vitro and in vivo. The Virtual Screen model that we employ uses multiple poses of the virtual compounds evaluating them via multiple criteria. Then an excel Pivot table is used to identify the duplicates with the logic being the more times a virtual compound appears with a good score it may be of interest to test in vitro. We are evaluating different beta-lactamases and ClpP proteases using different crystal structures then comparing the data from the different virtual screens. ADME studies are being performed on our top theoretical pharmaceutical hits. We have identified ractopamine as a μM inhibitor and a 50 μM inhibitor of a repurposed drug, in vitro against beta-lactamase. We think a novel method of identifying pharmaceutical hits has been revealed. The hope is to treat the patient with a Beta-lactamase inhibitor and then the normal penicillin like drug. ClpP protease is a new drug target, and we are hoping to discover novel inhibitors. Preliminary results appear encouraging, providing hope that a novel drug candidates will be identified and that our computational workflow will prove useful on other pharmaceutical targets