Union Is Strength: Target-Based and Whole-Cell High-Throughput Screens in Antibacterial Discovery

Abstract

Antimicrobial resistance is one of the greatest global health challenges today. For over three decades antibacterial discovery research and development has been focused on cell-based and target-based high throughput assays. Target-based screens use diagnostic enzymatic reactions to look for molecules that can bind directly and inhibit the target. Target-based screens are only applied to proteins that can be successfully expressed, purified and the activity of which can be effectively measured using a biochemical assay. Often times the molecules found in these in vitro screens are not active in cells due to poor permeability or efflux. On the other hand, cell-based screens use whole cells and look for growth inhibition. These screens give higher number of hits than target-based assays and can simultaneously test many targets of one process or pathway in their physiological context. Both strategies have pros and cons when used separately. In the past decade and a half our increasing knowledge of bacterial physiology has led to the development of innovative and sophisticated technologies to perform high throughput screening combining these two strategies and thus minimizing their disadvantages. In this review we discuss recent examples of high throughput approaches that used both target-based and whole-cell screening to find new antibacterials, the new insights they have provided and how this knowledge can be applied to other in vivo validated targets to develop new antimicrobials.

Development of a sensor for disulfide bond formation in diverse bacteria

“…Considering that disulfide bonds are required for the stability of virulence factors, toxins, antibiotic resistance, and cell envelope biogenesis proteins, lack of disulfide bond formation in many gram-negative pathogens results in virulence attenuation as well as antibiotic and phage susceptibility (6, 7, 21, 23, 45). However, the pathway is not essential for aerobic laboratory growth (17), thus facilitating the development of methods to search for molecules that identify molecules on-target in pathogenic bacteria, also known as target-based and whole cell-based approaches (46). The biosensor plasmids generated in this work could not only help to identify such Dsb inhibitors but also to study the variations of disulfide bond formation found in other bacteria (7, 14).…”

High-Throughput Screening of Natural Product and Synthetic Molecule Libraries for Antibacterial Drug Discovery

“…Combination strategies utilizing both CT-HTS and MT-HTS approaches are on the rise largely because they complement each other by circumventing their limitations of each other [ 24 ] and have been comprehensively discussed by Landeta and Meija-Santana [ 52 ]. Combined assays can help eradicate false positives but can be expensive and time-consuming.…”

Microbial Genomics: Innovative Targets and Mechanisms

“…Several pharmaceutical companies, including Abbott, Bayer, and GlaxoSmithKlin are working on discovering antibiotics that inhibit the growth of whole bacterial cells [30 In this way, the number of hits on the target can be increased, and a greater number o targets for a pathogen's physiological process or pathway can be tested [31]. Antibiotic discovered based on this method are the most marketable because they allow the bio chemical function of the target to be known even if certain elements are unknown sinc they have the advantage of targeting more than one target, but their mode of action (MOA is unknown [26,[32][33][34].…”