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 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.
Izu
H
H
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Japan.
Adachi
O
O
Yamada
M
M
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D001692:Biological Transport; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics; D005942:Gluconates / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D009876:Operon / Q000235:genetics*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D005942:Gluconates; C081598:GntR protein, E coli; C105741:GntU protein, E coli; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D000242:Cyclic AMP; D017853:Phosphotransferases (Alcohol Group Acceptor); C020578:gluconokinase; C030691:gluconic acid