On the cover, nitric oxide (NO) is a poison produced by the immune system to fend off microbes. In defense, Escherichia coli produce a NO dioxygenase (NOD, flavohemoglobin) and a NO reductase (NOR, flavorubredoxin) that protect critical Fe-S (de)hydratases and sustain growth. Modulon norRVW encodes a trascription regulator (R), a flavorubredoxin with a NO-binding diiron center (V), and a flavorubredoxin reductase (W). For details see the articles by Gardner et al., pages 8166-8171, 8172-8177.