Nitrate signalling on the nitrate reductase gene promoter depends directly on the activity of the nitrate transport systems in Chlamydomonas.
Nitrate signalling on the nitrate reductase (Nia1) gene promoter from Chlamydomonas reinhardtii has been studied by using a construct of the Nia1 promoter transcriptionally fused to the Chlamydomonas arylsulphatase gene as a reporter in strains bearing different sets of nitrate/nitrite transport genes. The high-affinity nitrate transport (HANT) system I is required for efficient signalling by nitrate, even at submicromolar concentrations of the anion. In addition, the autogenous regulation of nitrate reductase has been found to depend on the presence of system I. The low-affinity nitrate transport system III promoted signalling optimally on the promoter at millimolar nitrate concentrations. The HANT system IV, which is insensitive to ammonium and active at low CO2, allowed nitrate signalling at micromolar concentrations even in the presence of ammonium, suggesting that the balance of these two effectors controls Nia1 transcription. Our data indicate that nitrate signalling on the Nia1 gene promoter occurs intracellularly and depends on the activity of nitrate transporters.
Llamas
Angel
A
Departamento de Bioquímica y Biología Molecular, Campus de Rabanales, Edificio Severo Ochoa, Universidad de Córdoba, 14071-Córdoba, Spain.
Igeño
María Isabel
MI
Galván
Aurora
A
Fernández
Emilio
E
D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism; D001192:Arylsulfatases / Q000235:genetics / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics* / Q000378:metabolism; D000091285:Nitrate Transporters; D009566:Nitrates / Q000494:pharmacology*; D009573:Nitrites / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics*; D015800:Protozoan Proteins; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
D027321:Anion Transport Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C095726:NIT8 protein, Chlamydomonas reinhardtii; D000091285:Nitrate Transporters; D009566:Nitrates; D009573:Nitrites; D009687:Nuclear Proteins; D010940:Plant Proteins; D015800:Protozoan Proteins; D000644:Quaternary Ammonium Compounds; D011993:Recombinant Fusion Proteins; D002245:Carbon Dioxide; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D001192:Arylsulfatases