2. Academic Validation
  3. N-glycosylation of the human β1,4-galactosyltransferase 4 is crucial for its activity and Golgi localization

N-glycosylation of the human β1,4-galactosyltransferase 4 is crucial for its activity and Golgi localization

  • Glycoconj J. 2020 Oct;37(5):577-588. doi: 10.1007/s10719-020-09941-z.
Auhen Shauchuk 1,  Bożena Szulc 1,  Dorota Maszczak-Seneczko 1,  Wojciech Wiertelak 1,  Edyta Skurska 1,  Mariusz Olczak 2
Affiliations

Affiliations

  • 1 Faculty of Biotechnology, University of Wroclaw, 14A F. Joliot-Curie St., 50-383, Wroclaw, Poland.
  • 2 Faculty of Biotechnology, University of Wroclaw, 14A F. Joliot-Curie St., 50-383, Wroclaw, Poland. mariusz.olczak@uwr.edu.pl.
PMID: 32827291 DOI: 10.1007/s10719-020-09941-z
Abstract

β1,4-galactosyltransferase 4 (B4GalT4) is one of seven B4GalTs that belong to CAZy Glycosyltransferase family 7 and transfer galactose to growing sugar moieties of proteins, glycolipids, glycosaminoglycans as well as single sugar for lactose synthesis. Herein, we identify two asparagine-linked glycosylation sites in B4GalT4. We found that mutation of one site (Asn220) had greater impact on enzymatic activity while another (Asn335) on Golgi localization and presence of N-glycans at both sites is required for production of stable and enzymatically active protein and its secretion. Additionally, we confirm B4GalT4 involvement in synthesis of keratan sulfate (KS) by generating A375 B4GalT4 knock-out cell lines that show drastic decrease in the amount of KS proteoglycans and no significant structural changes in N- and O-glycans. We show that KS decrease in A375 cells deficient in B4GalT4 activity can be rescued by overproduction of either partially or fully glycosylated B4GalT4 but not with N-glycan-depleted B4GalT4 version.

Keywords

B4GalT4; CRISPR-Cas9; Golgi apparatus; Keratan sulfate; Mutagenesis; N-glycans.

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