Mutational analysis of the NH4+-nitrogen controls that regulate ammonium transport activity, heterocyst differentiation, nitrogenase activity and the heterocyst-spacing pattern in the cyanobacterium Nostoc muscorum.
Mutational analysis of the genetic determinants mediating NH(4+)-nitrogen regulating effects on NH(4+)-transport activity, heterocyst differentiation, nitrogenase activity and heterocyst pattern formation was carried out in Nostoc muscorum. Evidence suggested the operation of three separate genetic determinants in such nitrogen control; one mediating NH(4+)-repression control on both heterocyst formation and NH(4+)-transport activity, a second (Nif-R) mediating NH(4+)-repression control on nitrogenase synthesis/activity and a third (Pat-R) essential for intercalary heterocyst formation/distribution. Ammonia itself functioned as repressor signal of heterocyst formation and nitrogenase synthesis/activity and the glutamine synthetase enzyme played no role in the repression/derepression control of heterocyst development and functional nitrogenase formation.
Department of Biological Sciences, Rani Durgavathi University, Jabalpur, India.
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S
Singh
S K
SK
Hasija
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Negi
H N
HN
Singh
D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D001692:Biological Transport; D000458:Cyanobacteria / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D005798:Genes, Bacterial; D009584:Nitrogen / Q000378:metabolism / Q000493:pharmacokinetics / Q000502:physiology*; D009586:Nitrogen Fixation / Q000502:physiology; D009591:Nitrogenase / Q000096:biosynthesis / Q000378:metabolism*; D051922:PII Nitrogen Regulatory Proteins; D000644:Quaternary Ammonium Compounds / Q000378:metabolism / Q000493:pharmacokinetics*; D015534:Trans-Activators; D014157:Transcription Factors
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D051922:PII Nitrogen Regulatory Proteins; D000644:Quaternary Ammonium Compounds; D015534:Trans-Activators; D014157:Transcription Factors; D009591:Nitrogenase; D009584:Nitrogen