Three Nrt2 genes are differentially regulated in Chlamydomonas reinhardtii

Mol Gen Genet. 1998 May;258(4):373-7. doi: 10.1007/s004380050743.


Two new nitrate assimilation-related genes, Nrt2;3 and Nar5, have been identified in Chlamydomonas reinhardtii. The Nrt2;3 gene is a new member of the Nrt2 family, encoding high-affinity nitrate (nitrite) transporters. Like that of the nitrate assimilation genes, expression of the Nrt2;3 gene is down-regulated by ammonium and positively controlled by Nit2, a regulatory locus specific for the pathway. The three Nrt2 genes of C. reinhardtii are differentially regulated by the nitrogen source. Expression of Nrt2;3 and of Nrt2;1, a nitrate/nitrite-bispecific transporter gene, was induced by nitrate and more efficiently by nitrite. Accumulation of mRNA of Nrt2;2, the nitrate-specific transporter gene, was only induced efficiently by nitrate. The Nar5 gene is located upstream of the Nrt2;3 genomic region and expression of its mRNA is down-regulated by ammonium. The Nrt2;3 and Nar5 genes are overexpressed in a deletion mutant that lacks nitrate assimilation loci.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anion Transport Proteins*
  • Biological Transport, Active
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Chlamydomonas reinhardtii / genetics*
  • Chlamydomonas reinhardtii / metabolism
  • Down-Regulation
  • Gene Expression Regulation, Fungal*
  • Nitrates / metabolism
  • Plant Proteins*
  • Quaternary Ammonium Compounds / metabolism
  • Restriction Mapping


  • Anion Transport Proteins
  • Carrier Proteins
  • Nitrates
  • Plant Proteins
  • Quaternary Ammonium Compounds
  • nitrate transporters