Glucuronic acid can extend O-linked core 1 glycans, but it contributes only weakly to the negative surface charge of Drosophila melanogaster Schneider-2 cells

Breloy, Isabelle; Schwientek, Tilo; Lehr, Stefan; Hanisch, Franz-Georg

doi:10.1016/j.febslet.2008.04.003

« Previous Next »FEBS Letters
Volume 582, Issue 11 , Pages 1593-1598, 14 May 2008

Glucuronic acid can extend O-linked core 1 glycans, but it contributes only weakly to the negative surface charge of Drosophila melanogaster Schneider-2 cells☆

Edited by Felix Wieland

Isabelle Breloy
- Institute of Biochemistry II, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Köln, Germany
Tilo Schwientek
- Institute of Biochemistry II, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Köln, Germany
- This author contributed equally to the study as the first author.
Stefan Lehr
- German Diabetes Center, Heinrich-Heine-University, Düsseldorf, Germany
Franz-Georg Hanisch
- Institute of Biochemistry II, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Köln, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Köln, Germany
- Corresponding author. Address: Institute of Biochemistry II, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Köln, Germany. Fax: +49 221 478 7788.

Received 7 March 2008; accepted 4 April 2008. published online 14 April 2008.

Abstract

Previous studies of the mucin-type O-glycome of the fruit fly Drosophila melanogaster have revealed a restricted pattern of neutral core-type glycans corresponding to the Tn-(GalNAcα) and the T-antigen (Galβ1-3GalNAcα). In particular, no extension of the core 1 glycan with acidic sugars, like sialic acid, was detected. Here we report on the identification of an acidic O-linked trisaccharide expressed on secreted endogenous and recombinant glycoproteins of the embryonal hemocyte-like Drosophila Schneider-2 (S2) cell line. The glycan is composed of glucuronic acid, galactose and N-acetylgalactosamine and its structure was determined as GlcA1-3Gal1-3GalNAc. The O-linked trisaccharide resembles the peripheral structures of acidic D. melanogaster glycosphingolipids. Glucuronic acid may substitute for sialic acid in this organism, however its expression on the S2 cell surface may only marginally contribute to the negative surface charge as revealed by free-flow cell electrophoresis prior to and after β-glucuronidase treatment of the cells.

Abbreviations: EI, electron impact, ESI-MS, electrospray ionization-mass spectrometry, FFE, free-flow electrophoresis, IMAC, immobilized metal chelate affinity chromatography, GC/MS, gas chromatography–mass spectrometry, Gal, galactose, GalNAc, N-acetylgalactosamine, GlcA, glucuronic acid, Man, mannose, RP-HPLC, reversed phase high-pressure liquid chromatography, DG, dystroglycan, S2, Schneider-2