It is named FnrS because its expression is strongly dependent on fumarate and nitrate reductase regulator (FNR), a direct oxygen availability sensor.

[1][2] A conserved intergenic region between genes ydaN and dbpA was predicted to encode an sRNA, adjacent to where another non-coding RNA (C0343) has been identified.

[1] The majority of genes downregulated by FnrS are required for aerobic metabolism or the oxidative stress response.

[9] MarA activates genes involved in the resistance to superoxide,[10] which might not be necessary at the anaerobic conditions where FnrS is expressed.

[9] There is also evidence to suggest that the expression of FnrS is regulated by the RcsCDB signalling system in Salmonella enterica.