Investigating TamAB: a transporter implicated in outer membrane biogenesis of antimicrobial resistant bacteria

Antimicrobial resistant bacteria pose a significant threat to human health. The outer membrane (OM) of Gram-negative bacteria acts as a physical barrier against harmful molecules, such as antibiotics. Understanding the mechanisms behind OM biogenesis is essential to explore new targets for drug design.

In order to build and maintain their OM, bacteria must transport hydrophobic molecules, including lipids and proteins, from the inner to the OM, across the aqueous periplasm. However, many of these mechanisms are poorly understood.

This research project will focus on the TamAB, a large protein complex that spans across the periplasm and bridges the inner and OM. It is predicted to transport molecules to build or maintain the OM. TamAB is conserved across bacteria and plants, with homologues in humans, indicating it plays an important role that has been maintained throughout evolution.

Furthermore, bacteria lacking TamAB proteins show severe loss of OM homeostasis. This can result in loss of virulence, decreased antibiotic resistance, and even loss of viability. However, the functions of TamAB proteins remain remarkably understudied, highlighting an important area for further research.

This research aims to explore the function of TamAB in priority pathogen E. coli, using a combination of protein biochemistry, bacterial cell biology, and bacterial genetics. The function of TamAB is currently a hot topic in the field, and there is a debate over whether it transports lipids or proteins. To address this, this project will determine which components of the OM TamAB directly interact with.

This will be achieved using a combination of pull-downs, mass spectrometry, and site-specific crosslinking. Furthermore, the student will study the function of TamAB at the cellular level, by constructing gene knockouts and exploring phenotypes of these strains (e.g. changes in cell morphology changes, sensitivity to antimicrobials).

Overall, this research will increase our understanding of fundamental bacterial membrane biology, while identifying potential new candidates for the treatment of antimicrobial resistant bacterial infections, a key focus of the MRC research strategy.