Deficiency of UDP-galactose:N-acetylglucosamine β-1,4-galactosyltransferase I causes the congenital disorder of glycosylation type IId
Bengt Hanßke, Christian Thiel, Torben Lübke, Martin Hasilik, Stefan Höning, Verena Peters, Peter H. Heidemann, Georg F. Hoffmann, Eric G. Berger, Kurt von Figura, Christian Körner
Bengt Hanßke, Christian Thiel, Torben Lübke, Martin Hasilik, Stefan Höning, Verena Peters, Peter H. Heidemann, Georg F. Hoffmann, Eric G. Berger, Kurt von Figura, Christian Körner
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Article Genetics

Deficiency of UDP-galactose:N-acetylglucosamine β-1,4-galactosyltransferase I causes the congenital disorder of glycosylation type IId

Abstract

Deficiency of the Golgi enzyme UDP-Gal:N-acetylglucosamine β-1,4-galactosyltransferase I (β4GalT I) (E.C.2.4.1.38) causes a new congenital disorder of glycosylation (CDG), designated type IId (CDG-IId), a severe neurologic disease characterized by a hydrocephalus, myopathy, and blood-clotting defects. Analysis of oligosaccharides from serum transferrin by HPLC, mass spectrometry, and lectin binding revealed the loss of sialic acid and galactose residues. In skin fibroblasts and leukocytes, galactosyltransferase activity was reduced to 5% that of controls. In fibroblasts, a truncated polypeptide was detected that was about 12 kDa smaller in size than wild-type β4GalT I and that failed to localize to the Golgi apparatus. Sequencing of the β4GalT I cDNA and gene revealed an insertion of a single nucleotide (1031-1032insC) leading to premature translation stop and loss of the C-terminal 50 amino acids of the enzyme. The patient was homozygous and his parents heterozygous for this mutation. Expression of a corresponding mutant cDNA in COS-7 cells led to the synthesis of a truncated, inactive polypeptide, which localized to the endoplasmic reticulum.

Authors

Bengt Hanßke, Christian Thiel, Torben Lübke, Martin Hasilik, Stefan Höning, Verena Peters, Peter H. Heidemann, Georg F. Hoffmann, Eric G. Berger, Kurt von Figura, Christian Körner

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Figure 5

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Localization of the Golgi resident protein GP130 and the β4GalT I in con...
Localization of the Golgi resident protein GP130 and the β4GalT I in control (Co) and patient’s (M.S.) fibroblasts. (a) Western blot analysis of the wild-type (WT) β4GalT I and the 1031-1032insC mutant (left). The bars represent wild-type and mutant β4GalT I. TM denotes the transmembrane domain. The region carrying the O-glycans (E.G. Berger, unpublished data) is indicated in yellow. N112 indicates the single N-glycosylation site of β4GalT I. In the case of the patient, the five new C-terminal residues caused by the frame shift in the 1031-1032insC mutant are indicated in red (right). (b–g) Immunofluorescence double labeling of fibroblasts for GP130 (green, b and e) or β4GalT I (red, c and f) and an overlay of both (d and g). Increasing the concentration of the β4GalT I antibody tenfold above the standard concentration failed to detect β4GalT I in the patient’s fibroblasts. Bar in g: 10 μm.