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gltF , a member of the gltBDF operon of Escherichia coli , is involved in nitrogen‐regulated gene expression
Author(s) -
Castaño Irene,
Flores Noemi,
Valle Fernando,
Covarrubias Alejandra A.,
Bolivar Francisco
Publication year - 1992
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1992.tb01450.x
Subject(s) - operon , biology , complementation , gene , genetics , escherichia coli , open reading frame , l arabinose operon , microbiology and biotechnology , biochemistry , phenotype , peptide sequence
Summary We report here the construction and analysis of insertional mutations in each of the three genes of the gltBDF operon and the nucleotide sequence of the region downstream from gltD. Two open reading frames were identified, the first of which corresponds to gltF. The gltB and gltD genes code for the large and small subunits, respectively, of the enzyme glutamate synthase (GOGAT). gltF codes for a protein, with a molecular mass of 26350Da, which is required for Ntr induction. Histidase synthesis was determined as a measure of Ntr function. First, insertions in gltB, gltD or gltF all prevent Ntr induction. Second, complementation analysis indicates that high‐level expression of both the gltD and gltF genes is required for the induction of the Ntr enzymes under nitrogen‐limiting conditions, indicating that the phenotype of the gltB insertion probably results from polarity on gltD and gltF. Third, glutamate‐dependent repression of the glt operon appears to be mediated by the product of the gltF gene. Thus, the gltBDF operon of Escherichia coli is involved in induction of the so‐called Ntr enzymes in response to nitrogen deprivation, as well as in glutamate biosynthesis.