|Gene:||neuB||Accession Number: G-10744 (MetaCyc)|
Species: Escherichia coli K1
Subunit composition of
N-acetylneuraminate synthase = [NeuB]4
N-acetylneuraminate synthase subunit = NeuB
This enzyme has been shown by electrospray mass spectrometry to be a homotetramer, probably composed of two dimers. The primary active form is thought to be tetrameric [Huang05].
N-acetylneuraminate synthase (sialic acid synthase) participates in the biosynthesis of the α(2-8) poly-N-acetylneuraminate capsular polysaccharide of Escherichia coli K1, a virulence factor for this organism (in [Vann97].
This enzyme is distinguished from the eukaryotic enzyme EC 18.104.22.168 (example N-acetylneuraminate 9-phosphate synthase) which uses N-acetyl-D-mannosamine 6-phosphate as substrate, rather than N-acetyl-β-D-mannosamine.
The apparent molecular mass of the subunit was determined by SDS-PAGE [Vann97].
Gene Citations: [Annunziato95]
Molecular Weight of Polypeptide: 38.694 kD (from nucleotide sequence), 40.0 kD (experimental) [Vann97 ]
Relationship Links: Entrez-Nucleotide:PART-OF:U05248 , InterPro:IN-FAMILY:IPR006190 , InterPro:IN-FAMILY:IPR013132 , InterPro:IN-FAMILY:IPR013785 , InterPro:IN-FAMILY:IPR013974 , InterPro:IN-FAMILY:IPR020007 , Pfam:IN-FAMILY:PF03102 , Pfam:IN-FAMILY:PF08666 , Prosite:IN-FAMILY:PS50844 , Smart:IN-FAMILY:SM00858
Enzymatic reaction of: N-acetylneuraminate synthase
Synonyms: sialic acid synthase, N-acetylneuraminic acid synthase, N-acetylneuraminic acid synthetase, NeuAc synthase, sialate synthase
EC Number: 22.214.171.124
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is favored in the direction shown.
This enzyme catalyzes the condensation of N-acetyl-β-D-mannosamine with phosphoenolpyruvate, producing N-acetylneuraminate and phosphate (reviewed in [Tanner05]. The enzyme showed a high degree of substrate specificity [Vann97, Komaki97].
Inhibitors (Unknown Mechanism): Hg2+ [Komaki97] , Ag+ [Komaki97] , Cu2+ [Komaki97] , N-bromosuccinimide [Komaki97] , semicarbazide [Komaki97] , p-chloromercuribenzoate [Komaki97] , hydroxylamine [Komaki97] , I2 [Komaki97]
T(opt): 35 °C [Komaki97]
pH(opt): 7.5 [Komaki97]
Annunziato95: Annunziato PW, Wright LF, Vann WF, Silver RP (1995). "Nucleotide sequence and genetic analysis of the neuD and neuB genes in region 2 of the polysialic acid gene cluster of Escherichia coli K1." J Bacteriol 177(2);312-9. PMID: 7814319
Cox02: Cox AD, Hood DW, Martin A, Makepeace KM, Deadman ME, Li J, Brisson JR, Moxon ER, Richards JC (2002). "Identification and structural characterization of a sialylated lacto-N-neotetraose structure in the lipopolysaccharide of Haemophilus influenzae." Eur J Biochem 269(16);4009-19. PMID: 12180977
Hood99: Hood DW, Makepeace K, Deadman ME, Rest RF, Thibault P, Martin A, Richards JC, Moxon ER (1999). "Sialic acid in the lipopolysaccharide of Haemophilus influenzae: strain distribution, influence on serum resistance and structural characterization." Mol Microbiol 33(4);679-92. PMID: 10447878
Huang05: Huang HH, Liao HK, Chen YJ, Hwang TS, Lin YH, Lin CH (2005). "Structural characterization of sialic acid synthase by electrospray mass spectrometry--a tetrameric enzyme composed of dimeric dimers." J Am Soc Mass Spectrom 16(3);324-32. PMID: 15734325
Severi05: Severi E, Randle G, Kivlin P, Whitfield K, Young R, Moxon R, Kelly D, Hood D, Thomas GH (2005). "Sialic acid transport in Haemophilus influenzae is essential for lipopolysaccharide sialylation and serum resistance and is dependent on a novel tripartite ATP-independent periplasmic transporter." Mol Microbiol 58(4);1173-85. PMID: 16262798
Severi08: Severi E, Muller A, Potts JR, Leech A, Williamson D, Wilson KS, Thomas GH (2008). "Sialic acid mutarotation is catalysed by the Escherichia coli beta -propeller protein YJHT." J Biol Chem 283(8):4841-9. PMID: 18063573
Vann97: Vann WF, Tavarez JJ, Crowley J, Vimr E, Silver RP (1997). "Purification and characterization of the Escherichia coli K1 neuB gene product N-acetylneuraminic acid synthetase." Glycobiology 7(5);697-701. PMID: 9254051
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