Identification, characterization, and developmental expression of a novel alpha 2-->8-KDN-transferase which terminates elongation of alpha 2-->8-linked oligo-polysialic acid chain synthesis in trout egg polysialoglycoproteins.
A novel glycosyltransferase which catalyses transfer of deaminated neuraminic acid, KDN (2-keto-3-deoxy-D-glycero-D-galacto-nononic acid) from CMP-KDN to the non-reducing termini of oligo-polysialyl chains of polysialoglycoprotein (PSGP), was discovered in the ovary of rainbow trout (Oncorhynchus mykiss). The KDN-transferase activity was optimal at neutral pH, and stimulated 2 to 2.5-fold by 2-5 mM Mg2+ or Mn2+. Expression of KDN-transferase was developmentally regulated in parallel with expression of the alpha 2-->8-polysialyltransferase, which catalyses synthesis of the oligo-polysialyl chains in PSGP. Incorporation of the KDN residues into the oligo-polysialyl chains prevented their further elongation, resulting in 'capping' of the oligo-polysialyl chains. This is the first example of a glycosyltransferase that catalyses termination of alpha 2-->8-polysialylation in glycoproteins.
Angata
T
T
Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Japan.
Kitazume
S
S
Terada
T
T
Kitajima
K
K
Inoue
S
S
Troy
F A
FA
Inoue
Y
Y
D000818:Animals; D002240:Carbohydrate Sequence; D005260:Female; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss; D010063:Ovum / Q000378:metabolism*; D012794:Sialic Acids / Q000096:biosynthesis* / Q000737:chemistry; D012795:Sialoglycoproteins / Q000096:biosynthesis* / Q000737:chemistry; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
D012794:Sialic Acids; D012795:Sialoglycoproteins; C021319:polysialic acid; D012799:Sialyltransferases; C092858:alpha2-8-KDN-transferase