Life Science Case Study 2:
Understanding Bacterial Lifestyle Choices
Bacteria have been around much longer than humans on this planet. In fact one can argue that bacteria are much more evolved than we are, because they divide very rapidly compared to the nine months it takes for humans to reproduce. So we can try to understand where we’ve come from by going back to the evolutionary past to look at how bacteria do things. Bacteria which cause common diseases utilise the same procedures to communicate not only within themselves but to other bacteria, and how they communicate with the organism they are infecting.
Could you give some examples of bacteria you research, or particular signals that you look in to?
The sample that we concentrate most of the activities in the lab on is called Bacillus subtilis. What we try to do is extrapolate knowledge that we can obtain using this model system into other organisms which are less easy to work with in the lab but which do cause disease. We investigate the way in which this bacterium responds to changes in its environment that make it feel stressed. The changes in the environment can be simple things such as a change in temperature, a change in the pH of the soil it’s living in, even the imposition of blue light can cause stress to the bacterium. So what the bacterium tries to do is recover its healthy position by changing the patterns of proteins that are made, as a consequence of the stress, in order to deal with the stress.
What we work on is a signal transduction complex which we have called the ‘stressosome’, which is a large signalling complex which seems to funnel information within the cell to say that the cell is stressed through a series of different related signalling proteins so that then it directly it controls the change in pattern of gene expression.
How do you study this Stressosome, what do you look into about it?
What we’ve being doing bit by bit is to take the component parts of the Stressosome complex and look at the individual proteins using a technique called x-ray crystallography. We have used the macro-molecular crystallography beam lines at Diamond. To visualise these molecules you need to expose them to extremely bright sources of x-rays. It’s a bit like looking in the dark in your car with lights full beam or dipped headlights, you just see so much more with full beam.