@article {1279,
	title = {The enzymes of sialic acid biosynthesis},
	journal = {Bioorganic Chemistry},
	volume = {33},
	number = {3},
	year = {2005},
	note = {ISI Document Delivery No.: 931CJTimes Cited: 36Cited Reference Count: 59},
	month = {Jun},
	pages = {216-228},
	type = {Review},
	abstract = {The sialic acids are a family of nine carbon a-keto acids that play a wide variety of biological roles in nature. In mammals, they are found at the distal ends of cell surface glycoconjugates, and thus are major determinants of cellular recognition and adhesion events. In certain strains of pathogenic bacteria, they are found in capsular polysaccharides that mask the organism from the immune system by mimicking the exterior of a mammalian cell. This review outlines recent developments in the understanding of the two main enzymes responsible for the biosynthesis of the sialic acid, N-acetylneuraminic acid. The first, a hydrolyzing UDP-N-acetyl-glucosamine 2-epimerase, generates N-acetylmannosamine and UDP from UDP-N-acetylglucosamine. The second, sialic acid synthase, generates either N-acetylneuraminic acid (bacteria) or N-acetylneuraminic acid 9-phosphate (mammals) in a condensation reaction with phosphoenolpyruvate. An emphasis is placed on an understanding of the mechanistic and structural features of these enzymes. (c) 2005 Elsevier Inc. All rights reserved.},
	keywords = {2-EPIMERASE/N-ACETYLMANNOSAMINE KINASE, BIFUNCTIONAL KEY ENZYME, biosynthesis, ESCHERICHIA-COLI K1, FIRST 2, KDO8P SYNTHASE, MECHANISM, N-ACETYLGLUCOSAMINE 2-EPIMERASE, N-acetylmannosamine, N-ACETYLNEURAMINIC ACID, NEISSERIA-MENINGITIDIS, PHOSPHATE, phosphoenolpyruvate, RAT-LIVER, sialic acid synthase, STEPS, SYNTHASE GENE, UDP-GlcNAc 2-epimerase},
	isbn = {0045-2068},
	url = {<Go to ISI>://000229463100007},
	author = {Tanner, M. E.}
}
@article {1084,
	title = {Identification and characterization of NeuB3 from Campylobacter jejuni as a pseudaminic acid synthase},
	journal = {Journal of Biological Chemistry},
	volume = {280},
	number = {43},
	year = {2005},
	note = {ISI Document Delivery No.: 976IMTimes Cited: 22Cited Reference Count: 43},
	month = {Oct},
	pages = {35922-35928},
	type = {Article},
	abstract = {Campylobacter jejuni and Campylobacter coli are the main causes of bacterial diarrhea worldwide, and Helicobacter pylori is known to cause duodenal ulcers. In all of these pathogenic organisms, the flagellin proteins are heavily glycosylated with a 2-keto-3-deoxy acid, pseudaminic acid (5,7-diacetamido-3,5,7,9-tetradeoxy-L-glycero-L- manno-nonulosonic acid). The presence of pseudaminic acid is required for the proper development of the flagella and is thereby necessary for motility in, and invasion of, the host. In this study we report the first characterization of NeuB3 from C. jejuni as a pseudaminic acid synthase; the enzyme directly responsible for the biosynthesis of pseudaminic acid. Pseudaminic acid synthase catalyzes the condensation of phosphoenolpyruvate ( PEP) with the hexose, 2,4-diacetamido-2,4,6- trideoxy-L-altrose (6-deoxy-AltdiNAc), to form pseudaminic acid and phosphate. The enzymatic activity was monitored using H-1 and P-31 NMR spectroscopy, and the product was isolated and characterized. Kinetic analysis reveals that pseudaminic acid synthase requires the presence of a divalent metal ion for catalysis and that optimal catalysis occurs at pH 7.0. A coupled enzymatic assay gave the values for k(cat) of 0.65 +/- 0.01 s(-1), KmPEP of 6.5 +/- 0.4 mu M, and K(m)6-deoxy- AltdiNAc of 9.5 +/- 0.7 mu M. A mechanistic study on pseudaminic acid synthase, using[2-O-18] PEP, shows that catalysis proceeds through a C-O bond cleavage mechanism similar to other PEP condensing synthases such as sialic acid synthase.},
	keywords = {BISUBSTRATE INHIBITOR, ESCHERICHIA-COLI, HELICOBACTER-PYLORI, KDO8P SYNTHASE, NEISSERIA-MENINGITIDIS, O-SPECIFIC POLYSACCHARIDE, PNEUMOPHILA SEROGROUP-1 LIPOPOLYSACCHARIDE, PSEUDOMONAS-AERUGINOSA, SIALIC ACIDS, SOMATIC ANTIGENS},
	isbn = {0021-9258},
	url = {<Go to ISI>://000232726900019},
	author = {Chou, W. K. and Dick, S. and Wakarchuk, W. W. and Tanner, M. E.}
}
@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.}
}
