期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1989
卷号：86
期号：17
页码：6449-6453
DOI：10.1073/pnas.86.17.6449
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The nitrate reductase structural gene of Chlamydomonas reinhardtii has been isolated from a genomic library by using a nitrate reductase cDNA probe from barley. Restriction fragment length polymorphism analyses mapped the Chlamydomonas clone (B6a) to the nitrate reductase structural gene locus nit-1. Overlapping inserts cover a region of the genome of about 24 kilobases containing the entire gene, which spans approximately 5-8 kilobases. Sequence analysis of DNA fragments from the B6a clone demonstrated a high degree of sequence similarity at the amino acid level with regions corresponding to portions of the heme and FAD/NADH-binding domains of tobacco and Arabidopsis thaliana nitrate reductases and human NADH cytochrome b5 reductase. The identity of the cloned gene as nitrate reductase was confirmed by its ability to complement a nit-1 mutation upon transformation. The nitrate reductase gene produced a 3.4-kilobase transcript in cells derepressed with nitrate; the transcript was undetectable in cells grown in the presence of ammonium. In cells that contain a mutation in the putative regulatory gene nit-2, significantly lower levels of the 3.4-kilobase transcript were found, indicating that the wild-type nit-2 gene is involved in the control of nitrate reductase transcript levels.
