Aerobic expression of the nar operon of Escherichia coli in a fnr mutant

Mutations allowing aerobic expression of the anaerobically controlled nar operon have been located in the autoregulated fnr gene. Cloning and sequencing of the mutant fnrd20 allele, and fnr mRNA quantitation by dot blot assay, revealed that the mutation was the result of an IS5 insertion into the co...

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Published inMolecular microbiology Vol. 2; no. 3; p. 419
Main Authors Bonnefoy, V, Fons, M, Ratouchniak, J, Pascal, M C, Chippaux, M
Format Journal Article
LanguageEnglish
Published England 01.05.1988
Subjects
Alleles
Base Sequence
beta-Galactosidase - genetics
Chromosome Mapping
Cloning, Molecular
DNA Transposable Elements
DNA, Bacterial
DNA, Recombinant
Escherichia coli - enzymology
Escherichia coli - genetics
Gene Expression Regulation
Molecular Sequence Data
Mutation
Nitrate Reductase
Nitrate Reductases - genetics
Nucleic Acid Hybridization
Operon
Oxygen - metabolism
Plasmids
Transcription Factors - metabolism
Transduction, Genetic
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Summary:Mutations allowing aerobic expression of the anaerobically controlled nar operon have been located in the autoregulated fnr gene. Cloning and sequencing of the mutant fnrd20 allele, and fnr mRNA quantitation by dot blot assay, revealed that the mutation was the result of an IS5 insertion into the control region of fnr that enhanced transcription of the fnr gene at least ten-fold. Examination of the regulatory region of the negatively autoregulated fnr gene indicated that it shared homologous sequences with the positively Fnr-controlled frd and nar operons. The increase in fnr transcription in the fnrd20 mutated allele could be partly the result of loss of autoregulation, since the IS5 separated the Fnr target site from the '-35' region of the promoter.
ISSN:0950-382X
DOI:10.1111/j.1365-2958.1988.tb00047.x