PUBLICATION

Identification and biochemical characterization of two functional CMP-sialic acid synthetases in Danio rerio

Authors
Schaper, W., Bentrop, J., Ustinova, J., Blume, L., Kats, E., Tiralongo, J., Weinhold, B., Bastmeyer, M., and Muenster-Kuehnel, A.
ID
ZDB-PUB-120223-32
Date
2012
Source
The Journal of biological chemistry   287(16): 13239-13248 (Journal)
Registered Authors
Bastmeyer, Martin, Bentrop, Joachim
Keywords
enzymes, glycobiology, glycosylation, sialic acid, zebrafish, CMP-sialic acid synthetase
MeSH Terms
  • Gene Expression Regulation, Developmental/physiology
  • NIH 3T3 Cells
  • Cell Line, Tumor
  • Zebrafish/embryology
  • Zebrafish/genetics*
  • Animals
  • N-Acylneuraminate Cytidylyltransferase/chemistry
  • N-Acylneuraminate Cytidylyltransferase/genetics*
  • N-Acylneuraminate Cytidylyltransferase/metabolism
  • Gene Expression Regulation, Enzymologic/physiology
  • Cell Nucleus/enzymology
  • RNA, Messenger/genetics
  • Glycosylation
  • N-Acetylneuraminic Acid/metabolism
  • Substrate Specificity/physiology
  • Evolution, Molecular*
  • Mice
  • Molecular Sequence Data
  • Amino Acid Sequence
(all 19)
PubMed
22351762 Full text @ J. Biol. Chem.
Abstract

Sialic acids (Sia) form the non-reducing end of the bulk of cell surface expressed glycoconjugates. They are, therefore, major elements in intercellular communication processes. Addition of Sia to glycoconjugates requires metabolic activation to CMP-Sia, catalyzed by CMP-Sia synthetase (CMAS). This highly conserved enzyme is located in the cell nucleus in all vertebrates investigated to date, but its nuclear function remains elusive. Here, we describe the identification and characterization of two Cmas enzymes in Danio rerio (dreCmas), one of which exclusively localized in the cytosol. We show that the two cmas genes most likely originated from the third whole genome duplication which occurred at the base of teleost radiation. cmas paralogues were maintained in fishes of the Otocephala clade, while one copy got subsequently lost in Euteleostei (e.g. rainbow trout). In zebrafish, the two genes exhibited a distinct spatial expression pattern. The products of these genes (dreCmas1 and dreCmas2) diverged not only with respect to subcellular localization but also in substrate specificity. Nuclear dreCmas1 favored N-acetylneuraminic acid (Neu5Ac), while the cytosolic dreCmas2 showed highest affinity for 5-deamino-neuraminic acid (KDN). The subcellular localization was confirmed for the endogenous enzymes in fractionated zebrafish lysates. Nuclear entry of dreCmas1 was mediated by a bipartite nuclear localization signal, which seemed irrelevant for other enzymatic functions. With the current demonstration that in zebrafish two subfunctionalized cmas paralogues co-exist, we introduce a novel and unique model to detail the roles that CMAS has in the nucleus and in the sialylation pathways of animal cells.

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