@article {1464,
	title = {PseG of pseudaminic acid biosynthesis - A UDP-sugar hydrolase as a masked glycosyltransferase},
	journal = {Journal of Biological Chemistry},
	volume = {281},
	number = {30},
	year = {2006},
	note = {ISI Document Delivery No.: 065VFTimes Cited: 12Cited Reference Count: 40Liu, Feng Tanner, Martin E.},
	month = {Jul},
	pages = {20902-20909},
	type = {Article},
	abstract = {The flagellin proteins in pathogenic bacteria such as Campylobacter jejuni and Helicobacter pylori are heavily glycosylated with the nine-carbon alpha-keto acid, pseudaminic acid. The presence of this posttranslational modification is absolutely required for assembly of functional flagella. Since motility is required for colonization, pseudaminic acid biosynthesis represents a virulence factor in these bacteria. Pseudaminic acid is generated from UDP-N-acetylglucosamine in five biosynthetic steps. The final step has been shown to involve the condensation of 2,4-diacetamido- 2,4,6-trideoxy-L-altrose ( 6-deoxy-AltdiNAc) with phosphoenolpyruvate as catalyzed by the enzyme pseudaminic acid synthase, NeuB3. The 6-deoxy-AltdiNAc used in this process is generated from its nucleotide-linked form, UDP-6-deoxy-AltdiNAc, by the action of a hydrolase that cleaves the glycosidic bond and releases UDP. This manuscript describes the first characterization of a UDP-6-deoxy-AltdiNAc hydrolase, namely PseG ( Cj1312) from C. jejuni. The activity of this enzyme is independent of the presence of divalent metal ions, and the values of the catalytic constants were found to be k(cat) = 27 s(-1) and K-m = 174 mu M. The enzyme was shown to hydrolyze the substrate with an overall inversion of stereochemistry at C-1 and to utilize a C-O bond cleavage mechanism during catalysis. These results, coupled with homology comparisons, suggest that the closest ancestors to the hydrolase are members of the metal-independent GT-B family of glycosyltransferases that include the enzyme MurG.},
	keywords = {CAMPYLOBACTER-JEJUNI, FLAGELLIN, FUNCTIONAL-CHARACTERIZATION, GLYCOPROTEINS, glycosylation, HELICOBACTER-PYLORI, IDENTIFICATION, MECHANISM, N-ACETYLGLUCOSAMINE 2-EPIMERASE, NUDIX HYDROLASES, SYNTHASE},
	isbn = {0021-9258},
	url = {<Go to ISI>://000239187300027},
	author = {Liu, F. and Tanner, M. E.}
}
@article {4395,
	title = {UDP-N-trifluoroacetylglucosamine as an alternative substrate in N-acetylglucosaminyltransferase reactions},
	journal = {Carbohydrate Research},
	volume = {306},
	number = {1-2},
	year = {1998},
	note = {ISI Document Delivery No.: 100VZTimes Cited: 15Cited Reference Count: 28},
	month = {Jan},
	pages = {127-136},
	type = {Article},
	abstract = {The synthesis of UDP-N-trifluoroacetylglucosamine [uridine 5{\textquoteright}-(2-trifluoroacetamido-2-deoxy-alpha-D-glucopyranosyl diphosphate, UDP-GlcNAc-F-3] is reported. The compound is found to serve as a substrate for the {\textquoteright}core-2{\textquoteright} GlcNAc transferase (EC 2.4.1.102) that is involved in the biosynthesis, of O-linked glycoproteins and for the GlcNAcT-V transferase (EC 2.4. 1.155) that is a key biosynthetic enzyme controlling the branching pattern of cell surface complex Asn-linked oligosaccharides. The trisaccharide beta-o-Gal p-(1 {\textendash}> 3)-[beta-D-GlcpNAc-F-3(1 {\textendash}> 6)]alpha-D-GalpNAc-OR [R = (CH2)(8)CO2Me] was prepared from beta-D-Galp-(1 {\textendash}> 3)-alpha-D-GalpNAc-OR using the {\textquoteright}core-2{\textquoteright} GlcNAc transferase. The tetrasaccharide beta-D-GlcpNAc-(1 {\textendash}> 2)-[beta-D-GlcpNAc-F-3-(1 {\textendash}> 6)]-alpha-D-Manp-(1 {\textendash}> 6)-beta-D-Glcp-OR [R = (CH2)(7)CH3] was prepared from beta-D-GlcpNAc-(1 {\textendash}> 2)-alpha-D-Manp-(1 {\textendash}> 6)-beta-D-Glcp-OR [R = (CH2)(7)CH3] using the GlcNAcT-V transferase. Removal of the trifluoroacetyl group was achieved under mild basic conditions to give the corresponding glucosamine containing tetrasaccharide. These examples demonstrate the feasibility of introducing masked forms of glucosamine residues into oligosaccharides using GlcNAc-specific transferases. The requirement for the trifluoroacetamido group as a specific recognition element was evident in the observation that neither UDP-glucosamine nor UDP-glucose served as a donor substrates for the {\textquoteright}core-2{\textquoteright} GlcNAc transferase. (C) 1998 Elsevier Science Ltd. All rights reserved.},
	keywords = {GLYCOPROTEINS, N-acetylglucosaminyltransferase, OLIGOSACCHARIDE, OLIGOSACCHARIDES, ORGANIC-SYNTHESIS, RECOGNITION, SYNTHESIS, UDP-sugar analog},
	isbn = {0008-6215},
	url = {<Go to ISI>://000074837200012},
	author = {Sala, R. F. and MacKinnon, S. L. and Palcic, M. M. and Tanner, M. E.}
}
