The nitric oxide (NO)-sensing repressor NsrR of Neisseria meningitidis has a compact regulon of genes involved in NO synthesis and detoxification.
We have analyzed the extent of regulation by the nitric oxide (NO)-sensitive repressor NsrR from Neisseria meningitidis MC58, using microarray analysis. Target genes that appeared to be regulated by NsrR, based on a comparison between an nsrR mutant and a wild-type strain, were further investigated by quantitative real-time PCR, revealing a very compact set of genes, as follows: norB (encoding NO reductase), dnrN (encoding a protein putatively involved in the repair of nitrosative damage to iron-sulfur clusters), aniA (encoding nitrite reductase), nirV (a putative nitrite reductase assembly protein), and mobA (a gene associated with molybdenum metabolism in other species but with a frame shift in N. meningitidis). In all cases, NsrR acts as a repressor. The NO protection systems norB and dnrN are regulated by NO in an NsrR-dependent manner, whereas the NO protection system cytochrome c' (encoded by cycP) is not controlled by NO or NsrR, indicating that N. meningitidis expresses both constitutive and inducible NO protection systems. In addition, we present evidence to show that the anaerobic response regulator FNR is also sensitive to NO but less so than NsrR, resulting in complex regulation of promoters such as aniA, which is controlled by both FNR and NsrR: aniA was found to be maximally induced by intermediate NO concentrations, consistent with a regulatory system that allows expression during denitrification (in which NO accumulates) but is down-regulated as NO approaches toxic concentrations.
Heurlier
Karin
K
Department of Biology (Area 10), University of York, Heslington, York YO10 5YW, United Kingdom.
Thomson
Melanie J
MJ
Aziz
Naveed
N
Moir
James W B
JW
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D009345:Neisseria meningitidis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D018085:Regulon / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects
D001426:Bacterial Proteins; D020030:Nitric Oxide Donors; C091861:spermine nitric oxide complex; D013096:Spermine; D009569:Nitric Oxide