A bacteria cell's 'crisis command centre' has been observed for thefirst time swinging into action to protect the cell from external stressand danger, according to new research out today (3 October) in Science.
The research team behind today's study says that finding out exactly howbacteria respond and adapt to stresses and dangers is important becauseit will further their understanding of the basic survival mechanisms ofsome of the most resilient, hardy organisms on Earth.
The crisis command centre in certain bacteria cells is a large molecule,dubbed a 'stressosome' by the scientists behind today's research. Thesecells have around 20 stressosomes floating around inside them, andalthough scientists knew they played an important role in the cell'sresponse to stressful situations, the complexities of this process hadnot been fully understood until now.
If a bacteria cell finds itself in a dangerous situation - for example,if the temperature or saltiness of the bacteria's environment reachdangerous levels which threaten the survival of the bacteria -a warningsignal from the cell's surface is transmitted into the cell.
Using cutting edge electron microscopy imaging techniques the authors ofthe new research observed that the stressosomes receive this warningsignal, and in response several proteins called RSBT break away from thelarge stressosome. This breakaway triggers a cascade of signals withinthe cell which results in over 150 proteins being produced - proteinswhich enable the cell to adapt, react and survive in its newenvironment.
Professor Marin van Heel from Imperial College London's Department ofLife Sciences, one of the corresponding authors of the study, explains:"The cascade of events inside bacteria cells that occurs as a result ofstressosomes receiving warning signals leads to particular genes insidethe cell being transcribed more. This means that some genes alreadyactive inside the cell are 'turned up' so that levels of particularproteins in the cell increase. These changes to the protein make-up ofthe cell enable it to survive in a hostile or challenging environment."
Dr Jon Marles-Wright from Newcastle University says: "Our work showsthat cells respond to signals much like a dimmer on a light switch. Nowwe'll be building on this to work out how nature controls that dimmerswitch. We wouldn't have been able to carry out this work without accessto the Diamond synchrotron Light Source which has enabled us to examinethe structures of individual stressosome proteins at atomic resolution."
Dr Tim Grant, one of Imperial's post doctoral researchers, adds that thekey to bacteria cells' success at surviving in rapidly changingenvironments is their speedy response: "The cell's stressosomes are verygood at their job as crisis command centres because they provide a veryfast effective response to danger. The chain reaction they kickstartproduces results really quickly which enables bacteria to adapt tochanges in their surroundings almost instantaneously."
The team is now planning to collect very high resolution data of thestressosome complex on the world's newest high-resolution cryo electronmicroscope, the FEI "KRIOS" that has just been installed in the MaxPlanck Institute in Martinsried, Germany. Improving the resolution ofthe stressosome structure by a factor of two will lead to a resolutionrange normally only attainable by X-ray crystallography and will allowthe researchers to directly see the amino-acid components of thisfascinating complex.
Source: Imperial College London