Requirement of Nitric Oxide for Induction of Genes Whose Products Are Involved in Nitric Oxide Metabolism in Rhodobacter sphaeroides 2.4.3

• Published in: The Journal of biological chemistry 1996-10, Vol.271 (40), p.24382-24388
• Main Authors: Kwiatkowski, A V, Shapleigh, J P
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; beta-Galactosidase - genetics; Cloning, Molecular; Gene Expression Regulation, Bacterial - physiology; Genes, Bacterial; Hemoglobins - metabolism; Nitric Oxide - metabolism; Nitric Oxide - physiology; Nitroprusside - pharmacology; Operon; Rhodobacter sphaeroides; Rhodobacter sphaeroides - drug effects; Rhodobacter sphaeroides - genetics; Rhodobacter sphaeroides - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.271.40.24382

During denitrification, freely diffusible nitric oxide (NO) is generated for use as a terminal electron acceptor. NO is produced by nitrite reductase (Nir) and reduced to nitrous oxide by nitric oxide reductase (Nor). Using Nir and Nor-deficient mutants of Rhodobacter sphaeroides 2.4.3, we have shown that the endogenous production of NO or the addition of exogenous NO induces transcription of certain genes encoding Nir and Nor. A Nor-deficient strain was found to be capable of expressing wild type levels of nirK-lacZ and norB-lacZ fusions in medium unamended with nitrogen oxides. When this experiment is performed in the presence of hemoglobin, fusion expression is eliminated. NO and the NO-generator, sodium nitroprusside, can induce expression of both fusions in a strain lacking Nir and the consequent ability to produce NO. Sodium nitroprusside cannot induce expression of nirK-lacZ in a strain lacking the transcriptional activator NnrR (nitrite and nitric oxide reductase regulator). Addition of the cyclic nucleotides cAMP and 8-bromoguanosine-cGMP does not result in expression of either fusion. These results demonstrate that denitrifying bacteria produce NO as a signal molecule to activate expression of the genes encoding proteins required for NO metabolism.