Evaluation of druggability of MsbA proteins

• Grant number: 25/17834-9
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: December 01, 2025
• End date: November 30, 2028
• Field of knowledge: Biological Sciences - Biochemistry - Chemistry of Macromolecules
• Principal Investigator: Andrea Balan Fernandes
• Grantee: Yuri Rafael de Oliveira Silva
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 24/10255-0 - Structural and functional characterization of ABC transporters from ESKAPE microorganisms: tackling antimicrobial resistance, AP.SPEC

Abstract

Antimicrobial resistance (AMR) is an escalating global threat to public health. The inability to effectively control microbial infections has already led to a rise in mortality rates, while last-resort antibiotics are becoming increasingly ineffective against resistant microorganisms. This issue is exemplified by the growing prevalence of multi-drug resistant (MDR) bacterial strains. The ESKAPE group, consisting of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species, has been identified as a priority for addressing antimicrobial resistance (AMR). Bacteria employ various mechanisms to develop AMR, including active antibiotic efflux. This project seeks to study the molecular mechanisms that allow these bacteria to develop resistance to antimicrobial agents. The focus is on MsbA-like proteins, key drug efflux transporters in ESKAPE pathogens, which belong to the ATP-Binding Cassette (ABC) transporter family. These membrane proteins, primarily involved in lipid translocation and biofilm formation, also have a moonlighting function as exporters of foreign chemicals entities from cells, contributing to drug resistance. Inhibiting these transporters could restore bacterial susceptibility to existing antibiotics. To achieve this goal, this project proposes to employ structural and biophysical methods to study MsbA function and identify potential small-molecule inhibitors. Adopting a three-pronged strategy in the study of ESKAPE MsbA proteins: (i) to elucidate their structure and function; (ii) to devise methods and assays for assessing transport activities across various substrates; and (iii) to create a platform for structure-guided drug discovery targeting MsbAs, employing fragment-based techniques to identify potential inhibition sites on these enzymes. This postdoctoral project will focus on strategies (i) and (ii) to determine MsbA efflux pump structures from ESKAPE pathogens and key factors in antibiotic binding. Comparing orthologs will reveal shared and unique features. These methods will support a broader research program, advancing knowledge of an underexplored therapeutic target. Structural data will guide hit optimization into high-affinity inhibitors. (AU)