Bacterial nitric oxide synthases: what are they good for?

Trends Microbiol. 2009 May;17(5):212-8. doi: 10.1016/j.tim.2009.02.003. Epub 2009 Apr 15.


Nitric oxide synthases (NOSs) are heme-based monooxygenases that oxidize L-arginine to nitric oxide (NO), a signaling molecule and cytotoxic agent in higher organisms. Although NOS-like activity has been reported in many bacteria, only a few bacterial homologs of mammalian NOSs (mNOSs) have been characterized to date. In contrast to mNOSs, which possess both a catalytic and a reductase domain, the bacterial enzymes lack reductase domains and require the supply of suitable reductants to produce NO. A notable exception is a NOS from a gram-negative bacterium that contains a new type of reductase module. Remarkably, bacterial NOSs seem to have functions that differ from those of mNOSs, including nitration of different metabolites and protection against oxidative stress. Studies of bacterial NOSs will probably result in a better understanding of the mechanism of NO synthesis and unveil a variety of new functions for NO in microbes.

Publication types

  • Review

MeSH terms

  • Arginine / metabolism
  • Bacteria / enzymology*
  • Bacterial Physiological Phenomena*
  • Bacterial Proteins / metabolism*
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase / metabolism*
  • Oxidation-Reduction
  • Oxidative Stress
  • Stress, Physiological*


  • Bacterial Proteins
  • Nitric Oxide
  • Arginine
  • Nitric Oxide Synthase