title: Cloning of cellobiose phosphoenolpyruvate-dependent phosphotransferase genes: functional expression in recombinant Escherichia coli and identification of a putative binding region for disaccharides.
abstract: Genomic libraries from nine cellobiose-metabolizing bacteria were screened for cellobiose utilization. Positive clones were recovered from six libraries, all of which encode phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) proteins. Clones from Bacillus subtilis, Butyrivibrio fibrisolvens, and Klebsiella oxytoca allowed the growth of recombinant Escherichia coli in cellobiose-M9 minimal medium. The K. oxytoca clone, pLOI1906, exhibited an unusually broad substrate range (cellobiose, arbutin, salicin, and methylumbelliferyl derivatives of glucose, cellobiose, mannose, and xylose) and was sequenced. The insert in this plasmid encoded the carboxy-terminal region of a putative regulatory protein, cellobiose permease (single polypeptide), and phospho-beta-glucosidase, which appear to form an operon (casRAB). Subclones allowed both casA and casB to be expressed independently, as evidenced by in vitro complementation. An analysis of the translated sequences from the EIIC domains of cellobiose, aryl-beta-glucoside, and other disaccharide permeases allowed the identification of a 50-amino-acid conserved region. A disaccharide consensus sequence is proposed for the most conserved segment (13 amino acids), which may represent part of the EIIC active site for binding and phosphorylation.
authors.affiliation: Department of Microbiology and Cell Science, University of Florida, Gainesville 32611, USA.
authors.forename: X
authors.initials: X
authors.lastname: Lai
authors.forename: F C
authors.initials: FC
authors.lastname: Davis
authors.forename: R B
authors.initials: RB
authors.lastname: Hespell
authors.forename: L O
authors.initials: LO
authors.lastname: Ingram
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002475:Cellobiose / Q000378:metabolism*; D016384:Consensus Sequence; D017124:Conserved Sequence; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D015698:Genomic Library; D007709:Klebsiella / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics* / Q000378:metabolism*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D002475:Cellobiose; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C087821:phosphoenolpyruvate-cellobiose phosphotransferase; D001617:beta-Glucosidase