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PubMed1968

Effect of amino sugars on catabolite repression in Escherichia coli.

N-acetylglucosamine was found to be a good repressor source for catabolite repression of the beta-galactosidase system in Escherichia coli. It was found capable of increasing the severity of repression by glucose or gluconate when included in the medium with either of these substrates. N-acetylglucosamine was shown to be assimilated under these conditions, but had no effect on culture growth rates. Its influence on catabolite repression was not altered by growth in the presence of inhibiting levels of penicillin. These findings indicated that catabolite repression may be associated with certain reactions of amino sugar metabolism. A working model has been formulated along these lines and will be used to explore this possible relationship further.

Carbon Isotopes↗
PubMed1988

Differential mechanisms of feeding modulation induced by amino sugars in rats.

The present study examined and compared the effects of N-acetylglucosamine and 1-deoxy-N-acetylglucosamine on feeding behavior with those of glucosamine and 1-deoxyglucosamine. Infusion of 12 mu mole N-acetylglucosamine and 24 mu mole 1-deoxy-N-acetylglucosamine into the rat third cerebroventricle did not affect the feeding behavior. However, oral administration of 1200 mumol N-acetylglucosamine elicited feeding and 2400 mumol 1-deoxy-N-acetylglucosamine markedly suppressed feeding. These effects were abolished by truncal vagotomy. Both glucosamine and 1-deoxyglucosamine affected feeding by intra-third cerebroventricular and oral administration. These findings indicate that N-acetyl amino sugars modulate feeding behavior peripherally through the vagal afferent nerve.

Acetylglucosamine↗
PubMed1999

Convergent pathways for utilization of the amino sugars N-acetylglucosamine, N-acetylmannosamine, and N-acetylneuraminic acid by Escherichia coli.

N-Acetylglucosamine (GlcNAc) and N-acetylneuraminic acid (NANA) are good carbon sources for Escherichia coli K-12, whereas N-acetylmannosamine (ManNAc) is metabolized very slowly. The isolation of regulatory mutations which enhanced utilization of ManNAc allowed us to elucidate the pathway of its degradation. ManNAc is transported by the manXYZ-encoded phosphoenolpyruvate-dependent phosphotransferase system (PTS) transporter producing intracellular ManNAc-6-P. This phosphorylated hexosamine is subsequently converted to GlcNAc-6-P, which is further metabolized by the nagBA-encoded deacetylase and deaminase of the GlcNAc-6-P degradation pathway. Two independent mutations are necessary for good growth on ManNAc. One mutation maps to mlc, and mutations in this gene are known to enhance the expression of manXYZ. The second regulatory mutation was mapped to the nanAT operon, which encodes the NANA transporter and NANA lyase. The combined action of the nanAT gene products converts extracellular NANA to intracellular ManNAc. The second regulatory mutation defines an open reading frame (ORF), called yhcK, as the gene for the repressor of the nan operon (nanR). Mutations in the repressor enhance expression of the nanAT genes and, presumably, three distal, previously unidentified genes, yhcJIH. Expression of just one of these downstream ORFs, yhcJ, is necessary for growth on ManNAc in the presence of an mlc mutation. The yhcJ gene appears to encode a ManNAc-6-P-to-GlcNAc-6-P epimerase (nanE). Another putative gene in the nan operon, yhcI, likely encodes ManNAc kinase (nanK), which should phosphorylate the ManNAc liberated from NANA by the NanA protein. Use of NANA as carbon source by E. coli also requires the nagBA gene products. The existence of a ManNAc kinase and epimerase within the nan operon allows us to propose that the pathways for dissimilation of the three amino sugars GlcNAc, ManNAc, and NANA, all converge at the step of GlcNAc-6-P.

Acetylglucosamine↗