Artículo
Critical role of evolutionarily conserved glycosylation at Asn211in the intracellular trafficking and activity of sialyltransferase ST3Gal-II
Ruggiero, Fernando Miguel
; Vilcaes, Aldo Alejandro
; Iglesias Bartolome, Ramiro
; Daniotti, Jose Luis
Fecha de publicación:
07/2015
Editorial:
Portland Press
Revista:
Biochemical Journal
ISSN:
0264-6021
e-ISSN:
1470-8728
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
ST3Gal-II, a type II transmembrane protein, is the main mammalian sialyltransferase responsible for GD1a and GT1b ganglioside biosynthesis in brain. It contains two putative N-glycosylation sites (Asn92 and Asn211). Whereas Asn92 is only conserved in mammalian species, Asn211 is highly conserved in mammals, birds and fish. The present study explores the occupancy and relevance for intracellular trafficking and enzyme activity of these potential N-glycosylations in human ST3Gal-II. We found that ST3Gal-II distributes along the Golgi complex, mainly in proximal compartments. By pharmacological, biochemical and site-directed mutagenesis, we observed that ST3Gal-II is mostly N-glycosylated at Asn211 and that this co-translational modification is critical for its exit from the endoplasmic reticulum and proper Golgi localization. The individual N-glycosylation sites had different effects on ST3Gal-II enzymatic activity. Whereas the N-glycan at position Asn211 seems to negatively influence the activity of the enzyme using both glycolipid and glycoprotein as acceptor substrates, the single N-glycan mutant at Asn92 had only a moderate effect. Lastly, we demonstrated that the N-terminal ST3Gal-II domain containing the cytosolic, transmembrane and stem region (amino acids 1-51) is able to drive a protein reporter out of the endoplasmic reticulum and to retain it in the Golgi complex. This suggests that the C-terminal domain of ST3Gal-II depends on N-glycosylation to attain an optimum conformation for proper exit from the endoplasmic reticulum, but it does not represent an absolute requirement for Golgi complex retention of the enzyme.
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Articulos(CIQUIBIC)
Articulos de CENTRO DE INVEST.EN QCA.BIOL.DE CORDOBA (P)
Articulos de CENTRO DE INVEST.EN QCA.BIOL.DE CORDOBA (P)
Citación
Ruggiero, Fernando Miguel; Vilcaes, Aldo Alejandro; Iglesias Bartolome, Ramiro; Daniotti, Jose Luis; Critical role of evolutionarily conserved glycosylation at Asn211in the intracellular trafficking and activity of sialyltransferase ST3Gal-II; Portland Press; Biochemical Journal; 469; 1; 7-2015; 83-95
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