cis- and trans-acting elements involved in regulation of norB (norZ), the gene encoding nitric oxide reductase in Neisseria gonorrhoeae

Microbiology. 2008 Jan;154(Pt 1):226-239. doi: 10.1099/mic.0.2007/010470-0.


The ability of Neisseria gonorrhoeae to reduce nitric oxide (NO) may have important immunomodulatory effects on the host during infection. Therefore, a comprehensive understanding of the regulatory mechanism of the nitric oxide reductase gene (norB) needs to be elucidated. To accomplish this, we analysed the functional regions of the norB upstream region. The promoter contains an extended -10 motif (TGNTACAAT) that is required for high-level expression. Deletion and substitution analysis of the norB upstream region revealed that no sequence upstream of the -10 motif is involved in norB regulation under anaerobic conditions or in the presence of NO. However, replacement of a 29 bp inverted repeat sequence immediately downstream of the extended -10 motif gave high levels of aerobic expression of a norB : : lacZ fusion. Insertional inactivation of gonococcal nsrR, predicted to bind to this inverted repeat sequence, resulted in the loss of norB repression and eliminated NO induction capacity. Single-copy complementation of nsrR in trans restored regulation of both norB transcription and NorB activity by NO. In Escherichia coli, expression of a gonococcal nsrR gene repressed gonococcal norB; induction of norB occurred in the presence of exogenously added NO. NsrR also regulates aniA and dnrN, as well as its own expression. We also determined that Fur regulates norB by a novel indirect activation method, by preventing the binding of a gonococcal ArsR homologue, a second repressor whose putative binding site overlaps the Fur binding site.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Antigens, Bacterial / biosynthesis
  • Artificial Gene Fusion
  • Bacterial Outer Membrane Proteins / biosynthesis
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Genes, Reporter
  • Genetic Complementation Test
  • Models, Biological
  • Mutagenesis, Insertional
  • Neisseria gonorrhoeae / enzymology
  • Neisseria gonorrhoeae / genetics*
  • Oxidoreductases / genetics*
  • Point Mutation
  • Promoter Regions, Genetic*
  • Repetitive Sequences, Nucleic Acid
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Repressor Proteins / physiology*
  • Sequence Deletion
  • Trans-Activators / metabolism
  • beta-Galactosidase / biosynthesis
  • beta-Galactosidase / genetics


  • Antigens, Bacterial
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Repressor Proteins
  • Trans-Activators
  • aniA protein, Neisseria gonorrhoeae
  • ferric uptake regulating proteins, bacterial
  • Oxidoreductases
  • nitric-oxide reductase
  • beta-Galactosidase