Priority of pentose utilization at the level of transcription: arabinose, xylose, and ribose operons.
When E. coli cells were grown in minimal medium supplemented with D-ribose and D-xylose, a diauxic growth preferring D-xylose was observed. Transcription of the ribose (rbs) operon was repressed in the presence of D-xylose, phenotypically similar to catabolite repression by D-glucose, although D-ribose did not affect transcription of the xylose (xyl) operon. Complementation analysis with xylR revealed that the repression of the rbs operon by D-xylose is exerted at the transcriptional level through XylR, suggesting a novel mechanism for catabolite repression. Furthermore, it was shown that L-arabinose reduced transcriptions of both xyl and rbs operons, whereas the arabinose operon was not affected by D-xylose or D-ribose, suggesting a priority mechanism for pentose utilization.
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, Korea.
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Kang
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D001089:Arabinose / Q000235:genetics / Q000494:pharmacology; D001426:Bacterial Proteins; D002455:Cell Division / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics; D005798:Genes, Bacterial / Q000187:drug effects / Q000235:genetics; D009876:Operon / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D010429:Pentoses / Q000378:metabolism / Q000494:pharmacology*; D012097:Repressor Proteins / Q000235:genetics; D012266:Ribose / Q000235:genetics / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D014994:Xylose / Q000235:genetics / Q000494:pharmacology
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D010429:Pentoses; D012097:Repressor Proteins; D014157:Transcription Factors; C074322:XylR protein, Pseudomonas; D012266:Ribose; D014994:Xylose; D001089:Arabinose