The chitin disaccharide, N,N'-diacetylchitobiose, is catabolized by Escherichia coli and is transported/phosphorylated by the phosphoenolpyruvate:glycose phosphotransferase system.
We have previously reported that wild type strains of Escherichia coli grow on the chitin disaccharide N,N'-diacetylchitobiose, (GlcNAc)(2), as the sole source of carbon (Keyhani, N. O., and Roseman, S. (1997) Proc. Natl. Acad. Sci., U. S. A. 94, 14367-14371). A nonhydrolyzable analogue of (GlcNAc)(2,) methyl beta-N, N'-[(3)H]diacetylthiochitobioside ([(3)H]Me-TCB), was used to characterize the disaccharide transport process, which was found to be mediated by the phosphoenolpyruvate:glycose phosphotransferase system (PTS). Here and in the accompanying papers (Keyhani, N. O., Boudker, O., and Roseman, S. (2000) J. Biol. Chem. 275, 33091-33101; Keyhani, N. O., Bacia, K., and Roseman, S. (2000) J. Biol. Chem. 275, 33102-33109; Keyhani, N. O., Rodgers, M., Demeler, B., Hansen, J., and Roseman, S. (2000) J. Biol. Chem. 275, 33110-33115), we report that transport of [(3)H]Me-TCB and (GlcNAc)(2) involves a specific PTS Enzyme II complex, requires Enzyme I and HPr of the PTS, and results in the accumulation of the sugar derivative as a phosphate ester. The phosphoryl group is linked to the C-6 position of the GlcNAc residue at the nonreducing end of the disaccharide. The [(3)H]Me-TCB uptake system was induced only by (GlcNAc)(n), n = 2 or 3. The apparent K(m) of transport was 50-100 micrometer, and effective inhibitors of uptake included (GlcNAc)(n), n = 2 or 3, cellobiose, and other PTS sugars, i.e. glucose and GlcNAc. Presumably the PTS sugars inhibit by competing for PTS components. Kinetic properties of the transport system are described.
Department of Biology and the McCollum-Pratt Institute, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
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Keyhani
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Wang
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Lee
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Roseman
D001692:Biological Transport; D004187:Disaccharides / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D007700:Kinetics; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D010766:Phosphorylation; D014316:Tritium
D004187:Disaccharides; C103151:methyl beta-N,N'-diacetylthiochitobiose; D014316:Tritium; C010913:N,N-diacetylchitobiose; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System