Nitrogen oxide cycle regulates nitric oxide levels and bacterial cell signaling

Sci Rep. 2016 Feb 25:6:22038. doi: 10.1038/srep22038.

Abstract

Nitric oxide (NO) signaling controls various metabolic pathways in bacteria and higher eukaryotes. Cellular enzymes synthesize and detoxify NO; however, a mechanism that controls its cellular homeostasis has not been identified. Here, we found a nitrogen oxide cycle involving nitrate reductase (Nar) and the NO dioxygenase flavohemoglobin (Fhb), that facilitate inter-conversion of nitrate, nitrite, and NO in the actinobacterium Streptomyces coelicolor. This cycle regulates cellular NO levels, bacterial antibiotic production, and morphological differentiation. NO down-regulates Nar and up-regulates Fhb gene expression via the NO-dependent transcriptional factors DevSR and NsrR, respectively, which are involved in the auto-regulation mechanism of intracellular NO levels. Nitrite generated by the NO cycles induces gene expression in neighboring cells, indicating an additional role of the cycle as a producer of a transmittable inter-cellular communication molecule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / biosynthesis
  • Bacteria / genetics
  • Bacteria / metabolism*
  • Gene Expression Regulation, Bacterial
  • Nitrates / metabolism
  • Nitric Oxide / metabolism*
  • Nitrites / metabolism
  • Nitrogen Oxides / metabolism*
  • Oxygenases / metabolism
  • Signal Transduction*
  • Streptomyces coelicolor / genetics
  • Streptomyces coelicolor / metabolism

Substances

  • Anti-Bacterial Agents
  • Nitrates
  • Nitrites
  • Nitrogen Oxides
  • Nitric Oxide
  • Oxygenases
  • nitric oxide dioxygenase