Isolation and characterization of a ntrC mutant of Bradyrhizobium (Parasponia) sp. ANU289.
A mutant of Bradyrhizobium (Parasponia) sp. ANU289 affected in the regulation of nitrogen metabolism was isolated. The mutant, designated ANU293, was unable to induce ammonium transport (Amt), nitrate reductase (NR) or glutamine synthetase II (GSII) activities under conditions that induce these activities in the wild-type. However, glutamine synthetase I (GSI), which is expressed constitutively in the wild-type, was present at normal levels in the mutant. The mutant also retained the ability to fix nitrogen in vitro and in planta, although nodule development on siratro (Macroptilium atropurpureum) was retarded. Southern blot analysis showed that ntrC, the product of which is involved in regulation of nitrogen metabolism, is the site of pSUP1021 insertion in ANU293. These results indicate that the transcriptional activator NtrC is required for the expression of Amt, NR and GSII, but not GSI or nitrogenase in Bradyrhizobium (Parasponia) sp. ANU289.
Division of Biochemistry and Molecular Biology, Australian National University, Canberra ACT.
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Udvardi
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Lister
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Day
D000641:Ammonia / Q000378:metabolism; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins / Q000235:genetics*; D004790:Enzyme Induction; D015964:Gene Expression Regulation, Bacterial; D005974:Glutamate-Ammonia Ligase / Q000096:biosynthesis; D009154:Mutation; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000096:biosynthesis; D009586:Nitrogen Fixation / Q000235:genetics*; D051922:PII Nitrogen Regulatory Proteins; D012230:Rhizobiaceae / Q000235:genetics*; D013559:Symbiosis / Q000235:genetics; D015534:Trans-Activators; D014157:Transcription Factors
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D051922:PII Nitrogen Regulatory Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000641:Ammonia; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D005974:Glutamate-Ammonia Ligase