Sequencing and characterization of a gene cluster encoding the enzymes for L-rhamnose metabolism in Escherichia coli.
The sequencing of the EcoRI-HindIII fragment complementing mutations in the structural genes of the L-rhamnose regulon of Escherichia coli has permitted identification of the open reading frames corresponding to rhaB, rhaA, and rhaD. The deduced amino acid sequences gave a 425-amino-acid polypeptide corresponding to rhamnulose kinase for rhaB, a 400-amino-acid polypeptide corresponding to rhamnose isomerase for rhaA, and a 274-amino-acid polypeptide corresponding to rhamnulose-1-phosphate aldolase for rhaD. Transcriptional fusions of the three putative promoter regions to lacZ showed that only the rhaB leader region acted as a promoter, as indicated by the high beta-galactosidase activity induced by rhamnose, while no significant activity from the rhaA and rhaD constructions was detected. The rhaB transcription start site was mapped to -24 relative to the start of translation. Mutations in the catabolic genes were used to show that L-rhamnose may directly induce rhaBAD transcription.
Department of Biochemistry, School of Pharmacy, University of Barcelona, Spain.
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Moralejo
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Egan
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Hidalgo
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Aguilar
D000446:Aldehyde-Lyases / Q000235:genetics; D019747:Aldose-Ketose Isomerases; D000595:Amino Acid Sequence; D001482:Base Composition; D001483:Base Sequence; D002238:Carbohydrate Epimerases / Q000235:genetics; D003062:Codon; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D005810:Multigene Family; D010770:Phosphotransferases / Q000235:genetics; D017853:Phosphotransferases (Alcohol Group Acceptor); D015183:Restriction Mapping; D012210:Rhamnose / Q000378:metabolism*; D017385:Sequence Homology; D014158:Transcription, Genetic
D003062:Codon; D004269:DNA, Bacterial; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C062877:rhamnulokinase; D000446:Aldehyde-Lyases; C022526:rhamnulose-1-phosphate adolase; D002238:Carbohydrate Epimerases; D019747:Aldose-Ketose Isomerases; C062878:L-rhamnose isomerase; D012210:Rhamnose