Characterization of a chromosomally encoded, non-PTS metabolic pathway for sucrose utilization in Escherichia coli EC3132.
A wild-type isolate, EC3132, of Escherichia coli, that is able to grow on sucrose was isolated and its csc genes (mnemonic for chromosomally coded sucrose genes) transferred to strains of E. coli K12. EC3132 and all sucrose-positive exconjugants and transductants invariably showed a D-serine deaminase (Dsd)-negative phenotype. The csc locus maps adjacent to dsdA, the structural gene for the D-serine deaminase, and contains an inducible regulon, controlled by a sucrose-specific repressor CscR, together with structural genes for a sucrose hydrolase (invertase) CscA, for a D-fructokinase CscK, and for a transport system CscB. Based on DNA sequencing studies, this last codes for a hydrophobic protein of 415 amino acids. CscB is closely related to the beta-galactoside transport system LacY (31.2% identical residues) and a raffinose transport system RafB (32.3% identical residues) of the enteric bacteria, both of the proton symport type. A two-dimensional model common to the three transport proteins, which is based on the integrated consensus sequence, will be discussed.
Bockmann
J
J
Universität Osnabrück, Fachbereich Biologie/Chemie, FRG.
Heuel
H
H
Lengeler
J W
JW
D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport; D002876:Chromosomes, Bacterial; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005631:Fructokinases / Q000378:metabolism; D005798:Genes, Bacterial; D008040:Genetic Linkage; D006026:Glycoside Hydrolases / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D012097:Repressor Proteins / Q000378:metabolism; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D013395:Sucrose / Q000378:metabolism*; D043324:beta-Fructofuranosidase
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D012097:Repressor Proteins; C056379:cscB protein, E coli; D013395:Sucrose; D005631:Fructokinases; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C055701:phosphoenolpyruvate-sucrose phosphotransferase; C046173:fructokinase; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase