Professor Tracy Palmer FRSE FSB FAAM MEAM
Protein Transport in Bacteria
The major research focus of my group is the transport of proteins by the twin arginine protein transport pathway. This pathway, which is found in the cytoplasmic membranes of most bacteria, and the thylakoid membranes of plant chloroplasts, is highly unusual because it transports pre-folded proteins. Protein substrates are targeted to the Tat machinery by N-terminal signal peptides that contain an S/T- R-R-x-F-L-K ‘twin arginine’motif. Our aims are to study the function and mechanism of the Tat protein transporter, and the contribution that it makes to the physiology of bacteria.
Functional studies on the bacterial Tat pathway are carried out in collaboration with Dr Ben Berks, University of Oxford. Using the model organism Escherichia coli, we have identified the tatA, tatB, tatC and tatE genes that encode components of the Tat system. Focusing on the major components, TatA, B and C we are studying their roles in protein transport by a combination of genetics, molecular biology and biochemical techniques.
Our physiological studies on the Tat pathway currently encompass two groups of bacteria. Escherichia coli K12 has some 27 or so Tat substrate proteins. About two thirds of these contain non-covalently bound redox cofactors that are bound prior to export by the Tat pathway. We collaborate with Professor Frank Sargent to genetically define the components required for the assembly of these complex Tat substrates before their interaction with the Tat system. Other substrates of the E. coli Tat system include two amidase enzymes involved in cell wall remodelling and that are critical for cell envelope integrity. In collaboration with the Drug Discovery Unit in the College of Life Sciences we are interested in identifying small molecules that interfere with the activity of the Tat machinery that might be useful precursors to novel antimicrobial drugs
We have recently started collaborating with Prof Bill Hunter (Division of Biological Chemistry and Drug Discovery) to investigate the structure and function of Type VII protein secretion systems from Gram positive bacteria.
BI40051 - 4A05 Bacterial Membrane Biology
BI32052 Molecular Microbiology & Immunology
Jager, F., Zoltner, M., Kneuper, H., Hunter, W. N. and Palmer, T. (2016) Membrane interactions and self-association of components of the Ess/Type VII secretion system of Staphylococcus aureus. FEBS Lett
Palmer, T. and Berks, B. C. (2012) The twin-arginine translocation (Tat) protein export pathway. Nature reviews. Microbiology. 10, 483-496
Parkin, A., Bowman, L., Roessler, M. M., Davies, R. A., Palmer, T., Armstrong, F. A. and Sargent, F. (2012) How Salmonella oxidises H(2) under aerobic conditions. FEBS Lett. 586, 536-544
Rollauer, S. E., Tarry, M. J., Graham, J. E., Jaaskelainen, M., Jager, F., Johnson, S., Krehenbrink, M., Liu, S. M., Lukey, M. J., Marcoux, J., McDowell, M. A., Rodriguez, F., Roversi, P., Stansfeld, P. J., Robinson, C. V., Sansom, M. S., Palmer, T., Hogbom, M., Berks, B. C. and Lea, S. M. (2012) Structure of the TatC core of the twin-arginine protein transport system. Nature. 492, 210-214
Willemse, J., Ruban-Osmialowska, B., Widdick, D., Celler, K., Hutchings, M. I., van Wezel, G. P. and Palmer, T. (2012) Dynamic localization of Tat protein transport machinery components in Streptomyces coelicolor. J Bacteriol. 194, 6272-6281