title: Clustering of the nitrite reductase gene and a light-regulated gene with nitrate assimilation loci in Chlamydomonas reinhardtii.
abstract: Two new loci have been found to be clustered with five other genes for the nitrate assimilation pathway in the Chlamydomonas reinhardtii genome. One gene, located close to the 3'-end of the high-affinity nitrate transporter (HANT) gene Nrt 2; 2, corresponds to the nitrite reductase (NiR) structural gene Nii1. This is supported by a number of experimental findings: (i) NiR-deficient mutants have lost Nii1 gene expression; (ii) Nii1 mRNA accumulation is co-regulated with the expression of other structural genes of the nitrate assimilation pathway; (iii) nitrite (nitrate) utilization ability is recovered in the NiR mutants by functional complementation with a wild-type Nii1 gene; (iv) the elucidated NII1 amino acid sequence is highly similar to that of the cyanobacterial and higher-plant enzyme, and contains the predicted domains for plastidic ferredoxin-NiRs. Thus, the mutant phenotype and the mRNA sequence and expression of the Nii1 gene have been unequivocally related. Accumulation of mRNA for the second locus identified. Lde1 (light-dependent expression), was not regulated by nitrogen, but like nitrate-assimilation clustered genes, its expression was down-regulated in the dark.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Quesada
authors.forename: I
authors.initials: I
authors.lastname: Gómez
authors.forename: E
authors.initials: E
authors.lastname: Fernández
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects*; D005796:Genes; D008027:Light; D008969:Molecular Sequence Data; D005810:Multigene Family; D009566:Nitrates / Q000378:metabolism*; D009572:Nitrite Reductases / Q000235:genetics*; D011110:Polymorphism, Genetic; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
chemical_list: D018076:DNA, Complementary; D009566:Nitrates; D009572:Nitrite Reductases