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'-[H-3]diacetyl-thiochitobioside ([H-3]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 [H-3]Me-TCB and (GlcNAc), 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 [H-3]Me-TCB uptake system was induced only by (GlcNAc)(n), n = 2 or 3. The apparent K-m of transport was 50-100 muM, and effective inhibitors of uptake included (GlcNAc),, n = 2 or 3, cellobiose, and other PTS sugars, ie. glucose and GlcNAc. Presumably the PTS sugars inhibit by competing for PTS components. Kinetic properties of the transport system are described.