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1. Orientation of Membrane Proteins in Membranes

Supervisor: Alison Rodger (Chemistry)

Membrane proteins are important for allowing interactions between processes in different compartments of a cell. Biological membranes separate aqueous phases and provide a hydrophobic environment for membrane proteins to anchor and adopt a functional structure. The need for membrane proteins to be in a physiological environment, to avoid aggregation and to allow function, makes them more difficult to study than soluble proteins.

The aim of this miniproject was to investigate the possibility of inserting a membrane protein, from Escherichia coli and important for protein transport/translocation, into artificial membranes (liposomes). The ion channel gramicidin was used as a positive control. Circular dichroism was used to confirm the proteins had reasonable structural features/folding, and linear dichroism was used to show that they were oriented within the membrane in a reasonable way.

The membrane protein under investigation seemed to show a reasonable degree of alpha helical structure with some insertion into the lipsomes. A more thorough investigation would require looking at whether the membrane protein is active or inactive, and measuring the proportion of inserted compared to non-inserted protein.

2. Studying Protein Transport in Bacterial Cells Using GFP Bioimaging

Supervisor: Colin Robinson (Biology)

This project was the first half of an investigation into protein transport in bacterial cells. The twin-arginine translocation pathway of Escherichia coli was studied as an introduction to working in a Biological Sciences Research Laboratory.

The aim of this project was to become familiar with some of the experimental techniques currently used with a view to directing the Mathematical second half of the investigation, and yielding models and predictions useful in the laboratory.

3. Compartmental Modelling of the Sec and Tat Pathways of Escherichia coli

Supervisor: Markus Kirkilionis (Mathematics)

A compartmental model of protein translocation was constructed to describe the secretory pathway and the twin-arginine translocation pathway of Escherichia coli with a particular emphasis on details appropriate for the experimental design.

Present work on the secretory pathway and the twin-arginine translocation pathway concentrates on the function and assembly of the machinery involved in these pathways and we described ways in which compartmental modelling can contribute to these efforts.

The second and third miniprojects have been continued into a PhD project on the plant chloroplast Tat pathway making use of spatial modelling so we won't draw conclusions until the end of the work. ;)