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Research Fellows Directory

Tracy Palmer

Professor Tracy Palmer

Research Fellow


University of Dundee

Research summary

Bacteria are surrounded by one or more membranes which form a protective barrier. Secreting proteins into the environment requires that they are able to pass through the membrane barrier. In order to achieve this, bacteria have transporters located in the membrane that allow the passage of proteins. We study protein transporters in the bacterium Escherichia coli. These transporters are conserved in almost all bacteria and therefore E. coli is a convenient model system in which to study these processes. Until a few years ago it was generally believed that this

organism had a single protein transporter, termed the Sec system, which was responsible for the secretion of all of the 400 or so different proteins that are exported outside the bacterium. However, work in my group helped to establish

that there was a second type of protein transporter which we named the Tat system. The Sec transporter forms a very small channel in the membranes of bacteria that is only wide enough to allow unfolded proteins to pass through. By

contrast, the Tat system is unusual because it only transports proteins after they have already folded. Because folded proteins are much wider, this means that the Tat system has to form a bigger channel in the membrane. Additionally, because different folded proteins have different sizes, this means that the Tat system must be able to form channels of variable size, to accommodate the different diameters of the folded proteins that it transports. Our work aims to understand how the transport of folded proteins by the Tat system is achieved. This will not just satisfy our scientific curiosity, but might pave the way for the development of antibiotic compounds that jam the channel in an open form, killing bacteria. A detailed understanding of the Tat system also offers the potential to exploit the system to secrete ‘foreign’ proteins and opens up possibilities for bioengineering of bacteria to secrete proteins of pharmaceutical and industrial importance

Interests and expertise (Subject groups)

Grants awarded

Probing the mechanism of protein export by the bacterial Tat transport system

Scheme: Wolfson Research Merit Awards

Dates: Aug 2011 - Jul 2016

Value: £80,000

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