Scientists at the University of East Anglia (UEA) and Institut de Biologie Structurale (CEA-CNRS-UGA, France) have identified the structure of NsrR, a bacterial protein that binds to DNA and plays a key role in the bacterium’s resistance to nitric oxide (NO), which is produced in the initial immune response to infection.
In order to counter the effects of NO, which can be toxic to living organisms, many bacteria have evolved ways to detect it and mount a cellular response.
The most common, dedicated NO sensor in bacteria is the regulatory protein NsrR. Regulatory proteins bind to DNA, and in doing so control whether particular genes are switched on or off.
NsrR contains a specialised type of co-factor — an additional component of a protein needed for its activity — called an iron-sulfur cluster.
These are very fragile and reactive, which makes them hard to work with, but recent work in the Schools of Chemistry and Biology at UEA have provided important new information on how NsrR functions as a sensor of NO.