Gene organization and transcriptional regulation of the gntRKU operon involved in gluconate uptake and catabolism of Escherichia coli

We cloned and characterized the gntRKU operon encoding part of the GntI system involved in gluconate uptake and catabolism by Escherichia coli. The operon was shown to encode its repressor, a thermoresistant gluconate kinase, and a low affinity gluconate permease. CAT fusion analysis revealed that t...

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Bibliographic Details
Published in:Journal of molecular biology 1997-04, Vol.267 (4), p.778-793
Main Authors: Izu, Hanae, Adachi, Osao, Yamada, Mamoru
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Bacterial Proteins - genetics
Base Sequence
Biological Transport
Cloning, Molecular
Cyclic AMP - pharmacology
DNA-Binding Proteins - genetics
Escherichia coli
Escherichia coli - genetics
Escherichia coli Proteins
Gene Expression Regulation, Bacterial - genetics
Genes, Bacterial - genetics
gluconate kinase
gluconate permease
Gluconates - metabolism
gnt operon repressor
gntRKU operon
Membrane Transport Proteins
Models, Genetic
Molecular Sequence Data
Open Reading Frames - genetics
Operon - genetics
Phosphotransferases (Alcohol Group Acceptor) - genetics
Promoter Regions, Genetic - genetics
Recombinant Fusion Proteins
Repressor Proteins - genetics
Sequence Analysis, DNA
Sequence Homology, Amino Acid
Transcription Factors
Transcription, Genetic - genetics
transcriptional attenuation
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Summary:We cloned and characterized the gntRKU operon encoding part of the GntI system involved in gluconate uptake and catabolism by Escherichia coli. The operon was shown to encode its repressor, a thermoresistant gluconate kinase, and a low affinity gluconate permease. CAT fusion analysis revealed that the operon has a promoter for gntR and another for gntKU, and that the gntR gene is constitutively expressed, while that of gntKU is regulated positively by the cAMP-CRP complex and negatively by GntR. Read-through transcription from the gntR promoter into gntK was decreased in the presence of GntR, although GntR did not repress its own promoter. In addition, transcriptional attenuation was observed after the gntK gene, so gntU expression is reduced presumably to modulate the production of the low affinity gluconate permease according to the available concentration of gluconate.
ISSN:0022-2836
1089-8638
DOI:10.1006/jmbi.1996.0913