UDP-iV-acetylglucosamine

UDP-iV-acetylglucosamine S. aureus NCTC 8325, Mu50 Resistance and/or cell-... 

Williams, A.H., Raetz, C.R. Structural basis for the acyl chain selectivity and mechanism of UDP-IV-acetylglucosamine acyltransferase. Proc Natl Acad Sci USA 104 (2007) 13543-13550. 

The carbohydrate portion of glycoproteins is formed from UDP-iV-acetylglucosamine and CMP-A-acetylneuraminic acid, and is attached to the protein by A-glycosidic bonds to asparagine amide groups. 

Precursors of the peptidoglycan are UDP-iV-acetylglucosamine derived from iV-acetylglucosamine (D 1.1), and the peptide UDP-iV-acetylmuramyl-L-alanyl-D-glutamyl-L-lysyl (or diaminopimelyl)-D-alanyl-D-alanine formed from iV-acetyl-muramic acid. 

Phosphorus fungicides. These are a relatively new development. Kitazin P (12,26) (5-benzyl OO-di/sopropyl phosphorothionate) causes accumulation of UDP-iV-acetylglucosamine in fungal mycelia, even at 50 p.p.m. It is thought that a late step in the synthesis of cell-wall chitin is being prevented (Maeda et al, 1970). It is used systemically in rice-fields. 

Biosynthesis of bacterial cell wall is remarkable in two respects (1) It entails the synthesis of a regularly cross-linked polymer and (2) Part of the synthesis takes place inside the cell and part outside the cell. The synthesis of cell wall is divided into three stages, which occur at different locations (1) synthesis of UDP-/V-acetylmuramyl-penta-peptide, (2) polymerization of IV-acetylglucosamine and N-acetylmuramyl-pentapeptide to form linear peptidoglycan strands, and (3) cross-linking of the peptidoglycan strands. 

Figure 17-5. Synthesis of the mannose 6-phosphate recognition marker. R represents the high-mannose oligosaccharide of newly synthesized lysosomal enzymes. Reaction 1 is catalyzed by UDP-A,-acetylglucosamine lysosomal enzyme Ar-acetylglucosaminyl-1 -phosphotransferase. Reaction 2 is catalyzed by iV-acetylglucosamine-l-phosphodiester-iV-ace tylgluco saminidase.

Fig. 7. Biosynthesis of endotoxin in E. coli. The first step (1) in the pathway is catalyzed by UDP-A -acetylglucosamine (UDP-GlcNAc) acyltransferase (LpxA). (2) The committed step is catalyzed by the LpxC deacetylase, followed by (3) a second acyltransferase (LpxD). (4) Lipid X is generated by the removal of UMP from UDP-2,3-diacyl-GlcN by an unknown enzyme. (5) Lipid X and UDP-2,3-diacyl-GlcN are then condensed together by LpxD to form Lipid IV. (6) A 4 -kinase phos-phorylates the disaccharide to produce lipid IV. (7) Two consecutive additions of KDO by KdtA, and two 0-acylations by (8) HtrB and (9) MsbB yield KDOj-lipid A. Subsequent addition of core sugars and 0-antigen chains (not shown) yield the mature LPS.

Bacterial cell walls contain mureins which are polymers formed from UDP-Af-acetylglucosamine and UDP-iV-acetylmuramyl peptides. 

As will be discussed later (see Section IV) several monosaccharides besides glucose may be utilized in vivo as precursors of the carbohydrate components of glycoproteins. Glucosamine may enter the route toward UDP-lV-acetylglucosamine by direct phosphorylation to yield glucosamine 6-phosphate. Alternatively, it may be acetylated and subsequently phosphorylated by a specific kinase to yield N-acetylglucosamine 6-phos-... 

UDP-6-Deoxy-6-fluoro-D-galactose has been synthesized and then used as a donor substrate with a p-(l- 4)-galactosyltransferase and iV-acetylglucosamine to give 6 -deoxy-6 -fluoro-7V-acetyllactosamine. 5-Azido-3,5,6-trideoxy-3,6-di-fluoro-D-glucose has been prepared and was converted by hydrogenolysis into... 

M.T. Minowa, S. Oguri, A. Yoshida, T. Hara, A. Iwamatsu, H. Ikenaga, M. Takeuchi, cDNA cloning and expression of bovine UDP-N-acetylglucosamine alpha 1,3-D-mannoside beta 1,4-N-acetylglucosaminyltransferase IV, J Biol Chew, 1998, 273, 11556-11562. 

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