@article {1127,
	title = {Structural and mechanistic analysis of sialic acid synthase NeuB from Neisseria meningitidis in complex with Mn2+ phosphoenolpyruvate, and N-acetylmannosaminitol},
	journal = {Journal of Biological Chemistry},
	volume = {280},
	number = {5},
	year = {2005},
	note = {ISI Document Delivery No.: 897DJTimes Cited: 19Cited Reference Count: 58},
	month = {Feb},
	pages = {3555-3563},
	type = {Article},
	abstract = {In Neisseria meningitidis and related bacterial pathogens, sialic acids play critical roles in mammalian cell immunity evasion and are synthesized by a conserved enzymatic pathway that includes sialic acid synthase (NeuB, SiaC, or SynC). NeuB catalyzes the condensation of phosphoenolpyruvate (PEP) and N-acetylmannosamine, directly forming N-acetylneuraminic acid (or sialic acid). In this paper we report the development of a coupled assay to monitor NeuB reaction kinetics and an O-18-labeling study that demonstrates the synthase operates via a C-O bond cleavage mechanism. We also report the first structure of a sialic acid synthase, that of NeuB, revealing a unique domain-swapped homodimer architecture consisting of a (beta/alpha)(8) barrel (TIM barrel)type fold at the N-terminal end and a domain with high sequence identity and structural similarity to the ice binding type III antifreeze proteins at the C-terminal end of the enzyme. We have determined the structures of NeuB in the malate-bound form and with bound PEP and the substrate analog N-acetylmannosaminitol to 1.9 and 2.2 Angstrom resolution, respectively. Typical of other TIM barrel proteins, the active site of NeuB is located in a cavity at the C-terminal end of the barrel; however, the positioning of the swapped antifreeze-like domain from the adjacent monomer provides key residues for hydrogen bonding with substrates in the active site of NeuB, a structural feature that leads to distinct modes of substrate binding from other PEP-utilizing enzymes that lack an analogous antifreeze-like domain. Our observation of a direct interaction between a highly ordered manganese and the N-acetylmannosaminitol in the NeuB active site also suggests an essential role for the ion as an electrophilic catalyst that activates the N-acetylmannosamine carbortyl to the addition of PEP.},
	keywords = {3-DEOXY-D-ARABINO-HEPTULOSONATE-7-PHOSPHATE SYNTHASE, 3-DEOXY-D-MANNO-OCTULOSONATE-8-PHOSPHATE SYNTHASE, ACETYLNEURAMINIC ACID, BISUBSTRATE, CAMPYLOBACTER-JEJUNI, CATALYTIC MECHANISM, CELL GLYCOSYLATION, ENZYMATIC SYNTHESIS, ESCHERICHIA-COLI, INHIBITOR, KDO8P SYNTHASE},
	isbn = {0021-9258},
	url = {<Go to ISI>://000226983900053},
	author = {Gunawan, J. and Simard, D. and Gilbert, M. and Lovering, A. L. and Wakarchuk, W. W. and Tanner, M. E. and Strynadka, N. C. J.}
}
@article {5208,
	title = {Sugar nucleotide-modifying enzymes},
	journal = {Current Organic Chemistry},
	volume = {5},
	number = {2},
	year = {2001},
	note = {ISI Document Delivery No.: 411FKTimes Cited: 12Cited Reference Count: 170},
	month = {Feb},
	pages = {169-192},
	type = {Review},
	abstract = {Sugar nucleotides serve as the activated forms of carbohydrates that are used in a wide range of biosynthetic pathways. Instead of building up the sugar nucleotide from the free sugar itself, nature often chooses to modify the "donor" portion of a pre-existing sugar nucleotide in a biosynthetically efficient manner. In doing so a rich variety of catalytic strategies are employed and this review focuses on recent mechanistic and structural studies of the sugar nucleotide-modifying enzymes. The review is organized around the types of reactions catalyzed and contains the following sections: Epimerases/Mutases/Decarboxylases, Eliminations and Substitutions, Oxidation and Reduction, and Substitutions on the Periphery of Sugar Nucleotides.},
	keywords = {4, 6-DEHYDRATASE, 6-DIDEOXYHEXOSES, ACETYLGLUCOSAMINE 2-EPIMERASE/N-ACETYLMANNOSAMINE, ACETYLNEURAMINIC ACID, biosynthesis, CYTIDINE DIPHOSPHATE 3, D-GLUCOSE, ESCHERICHIA-COLI K-12, FIRST 2, GDP-FUCOSE SYNTHETASE, KINASE, N-ACETYLGLUCOSAMINE, SITE-DIRECTED MUTAGENESIS, STEPS, UDP-GALACTOSE 4-EPIMERASE},
	isbn = {1385-2728},
	url = {<Go to ISI>://000167487300004},
	author = {Tanner, M. E.}
}
