title: Characterization of the norB gene, encoding nitric oxide reductase, in the nondenitrifying cyanobacterium Synechocystis sp. strain PCC6803.
abstract: A norB gene encoding a putative nitric oxide reductase is present in the genome of the nondenitrifying cyanobacterium Synechocystis sp. strain PCC6803. The gene product belongs to the quinol-oxidizing single-subunit class of nitric oxide reductases, discovered recently in the denitrifier Ralstonia eutropha. Heterologous complementation of a nitric oxide reductase-negative mutant of R. eutropha with norB from Synechocystis restored nitric oxide reductase activity. With reduced menadione as the electron donor, an enzymatic activity of 101 nmol of NO per min per mg of protein was obtained with membrane fractions of Synechocystis wild-type cells. Virtually no nitric oxide reductase activity was present in a norB-negative mutant of Synechocystis. Growing cells of this mutant are more sensitive toward NO than wild-type cells, indicating that the presence of a nitric oxide reductase is beneficial for Synechocystis when the cells are exposed to NO. Transcriptional fusions with the chloramphenicol acetyltransferase reporter gene were constructed to monitor norB expression in Synechocystis. Transcription of norB was not enhanced by the addition of the NO-generating agent sodium nitroprusside.
authors.affiliation: Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Chausseestrasse 117, D-10115 Berlin, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Büsch
authors.forename: Bärbel
authors.initials: B
authors.lastname: Friedrich
authors.forename: Rainer
authors.initials: R
authors.lastname: Cramm
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D000458:Cyanobacteria / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D009154:Mutation; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D024483:Vitamin K 3 / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C095475:DNR protein, Pseudomonas aeruginosa; D014157:Transcription Factors; D009569:Nitric Oxide; D024483:Vitamin K 3; D010088:Oxidoreductases; C034747:nitric-oxide reductase