Far1, a Negative Regulatory Locus Required for the Repression of the Nitrate Reductase Gene in Chlamydomonas Reinhardtii
AUTOR(ES)
Zhang, D.
RESUMO
In Chlamydomonas reinhardtii, the genes required for nitrate assimilation, including the gene encoding nitrate reductase (NIT1), are subject to repression by ammonia. To study the mechanism of ammonia repression, we employed two approaches to search for mutants with defective repression of NIT1 gene expression. (1) PF14, a gene required for flagellar function, was used as a reporter gene for expression from the NIT1 promoter. When introduced into a pf14 mutant host, the NIT1:PF14 chimeric construct produced a transformant (T10-10B) with a conditional swimming phenotype. Spontaneous mutants with defective ammonia repression of the NIT1 promoter were screened for by isolating cells that gained constitutive motility. (2) Insertional mutagenesis was performed, followed by screening for chlorate sensitivity in the presence of ammonia ion. One insertional mutant and six spontaneous mutants were allelic and defined a new gene, FAR1 (free from ammonia repression). FAR1 was mapped to Linkage Group I, 7.7 cM to the right of the centromere. The far1-1 mutant strain was used to clone DNA adjacent to the site of plasmid insertion, which was then used as a hybridization probe to clone the FAR1 gene from wild type.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1207931Documentos Relacionados
- Isolation and characterization of the nitrate reductase structural gene of Chlamydomonas reinhardtii.
- Involvement of Reversible Inactivation in the Regulation of Nitrate Reductase Enzyme Levels in Chlamydomonas reinhardtii1
- Nitrite Reductase Mutants as an Approach to Understanding Nitrate Assimilation in Chlamydomonas reinhardtii1
- Nitrogen metabolite repression of nitrate reductase in Neurospora crassa: effect of the gln-1a locus.
- A chloroplast gene is required for the light-independent accumulation of chlorophyll in Chlamydomonas reinhardtii.