Bacteria use proteins to make sense of their environments
doi:10.1038/nindia.2019.88 Published online 12 July 2019
Using experiments and computer models, researchers have discovered that bacteria use specific proteins to sense their environments1. In fact, they use the proteins as sensors to detect the difference between a host and soil.
Previous studies have shown that bacteria can secrete specific proteins in response to environmental stimuli such as heat and changes in salt concentration. These proteins tell bacteria whether they have invaded a host or are living outside.
The molecular mechanism by which bacterial proteins sense such environmental changes is not clearly known. To throw light on this, scientists from the Indian Institute of Technology in Madras, India, and the University of Maryland, USA, studied Escherichia coli, a bacterium that thrives in the intestines and causes severe diarrhoea.
When exposed to different environmental conditions, the bacteria were found to activate cnu, a protein that has salt-regulating properties. Cnu binds to another protein called H-NS and endows the bacterium with abilities to adapt to changes in salt concentration and temperature.
The researchers, led by Athi N. Naganathan, demonstrated that cnu acts as an exquisite molecular sensor for detecting the ionic strength of a solution. The array of conformations that cnu acquires in response to changes in salt concentration are remarkably matched in the binding partner, H-NS, resulting in large changes in the binding properties and hence function.
Such molecular symphonies happen not just in bacteria but in cells of other organisms, the researchers say, adding that “what is shown here is just one of the many mechanisms that are possible”.
1. Narayan, A. et al. A binding cooperativity switch driven by synergistic structural swelling of an osmo-regulatory protein pair. Nat. Comm. Doi:10.1038/s41467-019-10002-9