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Clever microbes: bacterial sensors and signals

The views expressed are those of the author and are not necessarily those of Scientific American.


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If anyone is around in London over the weekend, there’s an awesome looking summer science exhibition at the Royal Society focusing on bacterial signal transduction: how bacteria work together to sense and respond to their environment. The exhibit runs from the 2-7th July and is free to attend. You can find out more about it, as well as ask questions for the scientists involved, on their website. For more information about the science, check out the exhibitor’s blog.

Exploring signalling systems is often a multidisciplinary process, requiring genetic research, mathematical modelling and evolutionary biology. A recent paper looking at the bacterial phage shock response uses all of these approaches to build up a picture of the complete signalling system.

The phage shock response system is used by bacteria to repair the inner cell membrane, for example following infection by bacteriophage. As bacteria use the gradient of protons across their cell membranes to generate energy, it is vital that any damage is repaired as quickly as possible. The phage shock response system is shared across many different Gram negative bacteria and in species such as Salmonella, Shigella, and Yersinia it may also be important for maintaining virulence. As it is shared across such a wide variety of species, the most important genes involved in the system can be determined by seeing which genes are most commonly conserved in working systems.

Number of orthologues (homologous gene sequences) of each gene in the phage shock protein system identified in the complete species set (white bar) and in the species of interest containing at least two orthologs of the PspA to G set (black bar). Image from the reference.

By analysing gene sharing between species, how the gene sequenced evolved over time, and changes in organisation of the genes, the researchers built up a picture of how important each gene was for the system to function, and how the role of each gene may have changed over time. They also examined the biological advantages and disadvantages of simpler versions of the system in environments of differing oxygen levels.

Their results suggest that there is a core gene response system consisting of a few genes, which has been supplemented and developed in different species to provide more sophisticated and nuanced response systems. These systems are able not just to respond to inner cell membrane damage, but to adapt that response depending on the outside environment. Furthermore, it is not just individual genes that have evolved and changed, the organisation of the genes within the DNA also differs in different species, and provides yet another level of regulation and control of the response system.

Reference: M. Huvet, T. Toni, X. Sheng, T. Thorne, G. Jovanovic, C. Engl, M. Buck, J.W. Pinney, and M.P.H. Stumpf, The Evolution of the Phage Shock Protein Response System: Interplay between Protein Function, Genomic Organization, and System Function, Mol Biol Evol (2011) 28 (3): 1141-1155

Featured image from the clever microbes tumblr.

Many thanks to the Royal Society for allowing me to reproduce the video interview clip.

S.E. Gould About the Author: A biochemist with a love of microbiology, the Lab Rat enjoys exploring, reading about and writing about bacteria. Having finally managed to tear herself away from university, she now works for a small company in Cambridge where she turns data into manageable words and awesome graphs. Follow on Twitter @labratting.

The views expressed are those of the author and are not necessarily those of Scientific American.





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