Differential regulation of the high affinity nitrite transport systems III and IV in Chlamydomonas reinhardtii.
Two high affinity nitrite transporters have been identified in Chlamydomonas reinhardtii. They have been named system III and system IV and shown to be differentially regulated by nitrogen and carbon supply. System III was induced under high CO(2) and required a micromolar nitrate signal for optimal expression, was inhibited by ammonium, and was not affected by either chloride or the chloride channel inhibitor 5-nitro-2-(3-phenylpropylamino)benzoic acid. System IV was induced optimally under limiting CO(2) and did not require nitrate signal, was inhibited by chloride and 5-nitro-2-(3-phenylpropylamino)benzoic acid, but was not affected by ammonium. Two transcripts that shared the expression pattern of systems III and IV activities were detected with an Nrt2;3 gene probe. In addition, a mutant defective in both the activity of system III and the expression of Nrt2;3 gene has been isolated. Genetic crosses and in vivo complementation studies indicate that this mutant is defective in a locus that is closely linked to the regulatory gene Nit2.
Rexach
J
J
Departamento de Bioquímica y Biología Molecular, Avenida San Alberto Magno s/n, Facultad de Ciencias, Universidad de Córdoba and Instituto Andaluz de Biotecnología, 14071 Córdoba, Spain.
Montero
B
B
Fernández
E
E
Galván
A
A
D000818:Animals; D027321:Anion Transport Proteins; D001693:Biological Transport, Active / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D002712:Chlorides / Q000494:pharmacology; D007700:Kinetics; D016296:Mutagenesis; D000091285:Nitrate Transporters; D009566:Nitrates / Q000378:metabolism; D009572:Nitrite Reductases / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D009579:Nitrobenzoates / Q000494:pharmacology; D010940:Plant Proteins; D017384:Sequence Deletion
D027321:Anion Transport Proteins; D002352:Carrier Proteins; D002712:Chlorides; D000091285:Nitrate Transporters; D009566:Nitrates; D009573:Nitrites; D009579:Nitrobenzoates; D010940:Plant Proteins; D002245:Carbon Dioxide; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D009572:Nitrite Reductases; C052695:nitrite reductase, copper-containing