MetaCyc Enzyme: cytidine 5'-monophosphate N-acetylneuraminate synthetase

Gene: Cmas Accession Number: G-11088 (MetaCyc)

Species: Rattus norvegicus

Subunit composition of cytidine 5'-monophosphate N-acetylneuraminate synthetase = [Cmas]2
         cytidine 5'-monophosphate N-acetylneuraminate synthetase subunit = Cmas

The native apparent molecular mass was determined by gel filtration chromatography [RodriguezAparic92].

This enzyme found in eukaryotes and prokaryotes has an important role in activation of sialic acids to their CMP-derivatives for use as a donor in sialyltransferase reactions. Its cloning, characterization, localization and structure have been reviewed [Kean04, MunsterKuhnel04]. In vertebrates this enzyme has been shown to be localized primarily in the nucleus and its amino acid sequence contains a nuclear localization signal and two nuclear export signals. The nuclear export signals are absent in the insect and bacterial enzymes [Fujita07].

In vertebrates it has been cloned from Homo sapiens, Mus musculus and Oncorhynchus mykiss (rainbow trout) although the substrate specificity for different sialic acids varies among species. Cytidine 5'-monophosphate N-acetylneuraminate synthetases are crucial in determining cellular sialylation patterns and are of interest as drug targets (in [Fujita05]). A simple assay for this enzyme has been developed to facilitate high-throughput analysis in rational drug design [Fujita05].

The native enzyme has been purified from rat [RodriguezAparic92] and bovine [Vionnet99] sources. In rat tissues, the enzyme has been detected in brain, kidney, heart, spleen, liver, stomach, intestine, lung, thymus, prostate and urinary bladder. However, it was not found in skeletal muscle [RevillaNuin98].

The subunit structure has been reported to vary among species. The native rat enzyme was determined to be a homodimer [RodriguezAparic92]. The mouse enzyme (see cytidine 5'-monophosphate N-acetylneuraminate synthetase) was proposed to be a homotetramer consisting of two dimers, based on crystal structure analysis of the N-terminal catalytic domain [Krapp03]. However, the functionally active unit for the mouse and bacterial enzyme is the homodimer. Homotetramer formation may explain the oligomerization seen during purification of the enzyme from different species (reviewed in [MunsterKuhnel04]).
The subunit apparent molecular mass was determined by SDS-PAGE [RodriguezAparic92].

Locations: nucleus

Molecular Weight of Polypeptide: 48.129 kD (from nucleotide sequence), 58.0 kD (experimental) [RodriguezAparic92 ]

Molecular Weight of Multimer: 116.0 kD (experimental) [RodriguezAparic92]

Unification Links: Pride:P69060 , Protein Model Portal:P69060 , SMR:P69060 , String:10116.ENSRNOP00000018734 , UniProt:P69060

Relationship Links: Entrez-Nucleotide:PART-OF:AABR00000000 , InterPro:IN-FAMILY:IPR003329 , InterPro:IN-FAMILY:IPR023214 , InterPro:IN-FAMILY:IPR029044 , Pfam:IN-FAMILY:PF02348

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

GO Terms:

Cellular Component: GO:0005634 - nucleus [RodriguezAparic92]

Created 26-Feb-2009 by Fulcher CA , SRI International

Enzymatic reaction of: cytidine 5'-monophosphate N-acetylneuraminate synthetase

Synonyms: cytidine 5'-monophosphate N-acetylneuraminic acid synthetase, N-acylneuraminate cytidylyltransferase, CMP-N-acetylneuraminic acid synthetase, CMP-NeuNAc synthetase, CMP-sialic acid synthetase, cytidine monophosphate sialic acid synthetase

N-acetyl-β-neuraminate + CTP <=> CMP-N-acetyl-β-neuraminate + diphosphate

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.

Alternative Substrates for N-acetyl-β-neuraminate: N-glycoloyl-neuraminate [RodriguezAparic92 ]

In Pathways: superpathway of sialic acids and CMP-sialic acids biosynthesis , CMP-N-acetylneuraminate biosynthesis I (eukaryotes)

The enzyme required Mg2+ for activity, but it could be replaced by the divalent cations shown. It was highly specific for CTP. It was also inhibited by its product, CMP-N-acetyl-β-neuraminate [RodriguezAparic92].

Cofactors or Prosthetic Groups: Mg2+ [RodriguezAparic92], Mn2+ [RodriguezAparic92], Ca2+ [RodriguezAparic92], Co2+ [RodriguezAparic92]

Activators (Unknown Mechanism): 2-mercaptoethanol [RodriguezAparic92] , L-dithiothreitol [RodriguezAparic92]

Inhibitors (Competitive): CDP [RodriguezAparic92] , CMP [RodriguezAparic92] , dTTP [RodriguezAparic92] , UTP [RodriguezAparic92] , ATP [RodriguezAparic92] , GTP [RodriguezAparic92]

Inhibitors (Unknown Mechanism): CMP-N-acetyl-β-neuraminate [RodriguezAparic92] , N-ethylmaleimide [RodriguezAparic92] , p-hydroxymercuribenzoate [RodriguezAparic92] , 5,5'-dithio-bis-2-nitrobenzoate [RodriguezAparic92] , Hg2+ [RodriguezAparic92] , Fe2+ [RodriguezAparic92] , ammonium sulfate [RodriguezAparic92] , Cu2+ [RodriguezAparic92] , Zn2+ [RodriguezAparic92]

Kinetic Parameters:

Km (μM)

T(opt): 45 °C [RodriguezAparic92]

pH(opt): 8.0 [RodriguezAparic92]


Fujita05: Fujita A, Sato C, Munster-Kuhnel AK, Gerardy-Schahn R, Kitajima K (2005). "Development of a simple and efficient method for assaying cytidine monophosphate sialic acid synthetase activity using an enzymatic reduced nicotinamide adenine dinucleotide/oxidized nicotinamide adenine dinucleotide converting system." Anal Biochem 337(1);12-21. PMID: 15649371

Fujita07: Fujita A, Sato C, Kitajima K (2007). "Identification of the nuclear export signals that regulate the intracellular localization of the mouse CMP-sialic acid synthetase." Biochem Biophys Res Commun 355(1);174-80. PMID: 17292865

Kean04: Kean EL, Munster-Kuhnel AK, Gerardy-Schahn R (2004). "CMP-sialic acid synthetase of the nucleus." Biochim Biophys Acta 1673(1-2);56-65. PMID: 15238249

Krapp03: Krapp S, Munster-Kuhnel AK, Kaiser JT, Huber R, Tiralongo J, Gerardy-Schahn R, Jacob U (2003). "The crystal structure of murine CMP-5-N-acetylneuraminic acid synthetase." J Mol Biol 334(4);625-37. PMID: 14636592

MunsterKuhnel04: Munster-Kuhnel AK, Tiralongo J, Krapp S, Weinhold B, Ritz-Sedlacek V, Jacob U, Gerardy-Schahn R (2004). "Structure and function of vertebrate CMP-sialic acid synthetases." Glycobiology 14(10);43R-51R. PMID: 15201214

RevillaNuin98: Revilla-Nuin B, Reglero A, Feo JC, Rodriguez-Aparicio LB, Ferrero MA (1998). "Identification, expression and tissue distribution of cytidine 5'-monophosphate N-acetylneuraminic acid synthetase activity in the rat." Glycoconj J 15(3);233-41. PMID: 9579800

RodriguezAparic92: Rodriguez-Aparicio LB, Luengo JM, Gonzalez-Clemente C, Reglero A (1992). "Purification and characterization of the nuclear cytidine 5'-monophosphate N-acetylneuraminic acid synthetase from rat liver." J Biol Chem 267(13);9257-63. PMID: 1577759

Vionnet99: Vionnet J, Concepcion N, Warner T, Zapata G, Hanover J, Vann WF (1999). "Purification of CMP-N-acetylneuraminic acid synthetase from bovine anterior pituitary glands." Glycobiology 9(5);481-7. PMID: 10207180

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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