Microbiologists from Trinity College Dublin have discovered that an identical protein is used differently by two species of bacteria to help them cope with distinct types of environmental stress. The discovery reveals an extraordinary level of versatility in the way different genes are ‘switched on’ in bacteria, which in turn helps to explain how they evolve so quickly.
The microbiologists showed that the same protein, called ‘OmpR’, which is responsible for binding to specific sections of DNA, governs the way a large cohort of genes function in both a human-friendly strain of Escherichia coli (E. coli) and in the potentially deadly Salmonella enterica serovar Typhimurium (S. Typhimurium).
In E. coli, OmpR is central to the ability of the bacterium to survive sudden stress caused by water moving in and out of its cells due to changing external conditions. In S. Typhimurium, however, OmpR is a key regulator of a series of actions that enable individual bacteria to respond to and survive acid stress. Such conditions are experienced, for example, in the hostile environment found in the bacteria-destroying vacuoles of macrophages, which are cells of the immune system that Salmonella can defeat using specialist pathogenic genes.
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