Our understanding of the factors that influence compound accumulation into Gram-negative bacteria is significantly lacking as evidenced by the dearth of new leads arising from large-scale biochemical or target-agnostic phenotypic antibacterial screening efforts. This knowledge gap stems from the historical lack of predictive cellular assays, tools, and models that provide structure-activity relationships to inform optimization of compound accumulation. To address this gap, we developed a sensitive and specific whole-cell approach in Escherichia coli called titrable outer membrane protein assay system (TOMAS). We used TOMAS to characterize the structure porin-permeation relationships of the Pseudomonas aeruginosa porin OprD and the Acinetobacter baumannii porin OmpA. A novel set of carbapenem analogs was used to explore the structure-permeation relationship for permeation through OprD. Our results suggest that small structural modifications, especially the number and nature of charges and hydrogen bonding groups and their position, have dramatic effects on the ability of these molecules to permeate into cells through OprD. We identified OmpA as the porin responsible for the uptake for the β-lactamase inhibitor ETX2514 in A. baumannii and have observed comparable results where small structural changes impact the ability of these small molecules to permeate into this serious Gram-negative pathogen. Taken together these results highlight the need to develop a better understanding of structure-permeation relationships.

Obstacles to the discovery of novel antibacterials & approaches towards a new strategy

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.