Position: Professor of Molecular
Microbiology and Head of the Division of Molecular Microbiology
Division: Molecular Microbiology
Address: College of Life Sciences,
University of Dundee,
Dundee
Telephone: +44 1382 386464, int ext. 86464
Email: t.palmer@dundee.ac.uk
Website: Palmer Lab
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
Soil-dwelling Streptomyces is an important group of Gram positive bacteria that produce many commercially important antibiotic compounds. The genome of the model strain, S. coelicolor encodes a large number of probable Tat substrate proteins. We are using a variety of methods, including genetics and proteomics, to define the roles that the Tat pathway plays in the physiology of S. coelicolor and its possible exploitation for biotechnology applications. We are also investigating the Tat pathway of S. scabies in collaboration with Professor Rosemary Loria . This organism causes potato scab, and our experimental evidence suggests that the Tat pathway makes a major contribution to the virulence of the organism.
