N‐glycans harboring the Lewis a epitope are expressed at the surface of plant cells

Abstract

In plants, N-linked glycans are processed in the Golgi apparatus to complex-type N-glycans of limited size containing a beta(1,2)-xylose and/or an alpha(1,3)-fucose residue. Larger mono- and bi-antennary N-linked complex glycans have not often been described. This study has re-examined the structure of such plant N-linked glycans, and, through both immunological and structural data, it is shown that the antennae are composed of Lewis a (Le(a)) antigens, comprising the carbohydrate sequence Gal beta 1-3[Fuc alpha 1-4]GlcNAc. Furthermore, a fucosyltransferase activity involved in the biosynthesis of this antigen was detected in sycamore cells. This is the first characterization in plants of a Lewis antigen that is usually found on cell-surface glycoconjugates in mammals and involved in recognition and adhesion processes. Le(a)-containing N-linked glycans are widely distributed in plants and highly expressed at the cell surface, which may suggest a putative function in cell/cell communication.

Structure and Substrate Specificity of a Eukaryotic Fucosidase from Fusarium graminearum

“…These include fungal and bacterial ␣-fucosidases (domain identities: 25-92%, with the highest identity for a putative F. pseudograminearum protein, GenBank TM accession number EKJ77323.1) and various other bacterial glycoside hydrolases acting on a variety of substrates (domain identities: 25-41%). The latter include glycoside hydrolase family 5,16,19,28,54,64,76, and 81 (classified in CAZy database). Most of these glycoside hydrolases contain the (N/D)(N/D)XX(S/T)S motif of the crystallin domain except the GH29 fucosidases and a putative GH54 ␣-L-arabinofuranosidase B family protein (GenBank TM ADO68190.1), both of which remove terminal sugars from branched glycans.…”

“…The first function is analogous to the function of fucosylation in mammal, serving a regulatory function. Fucosylation is believed to be involved in cell to cell communication in plants (5) and in reproductive development during flowering (6). Fucose appears to also have a second, structural function in plants in the form of terminal side chain modifications of cell wall polysaccharides including hemicellulose xyloglucan and pectin.…”

The N‐terminal 77 amino acids from tobacco N‐acetylglucosaminyltransferase I are sufficient to retain a reporter protein in the Golgi apparatus of Nicotiana benthamiana cells

“…Both antibody incubations were carried out for 60 min followed by three washing steps with the blocking solution after the primary incubation and with MTSB after the secondary incubation. As primary antibody a rabbit anti-Le a monoclonal antibody [11] was used, the secondary antibody was a Cy3 conjugated sheep anti-rabbit antibody (Sigma). As anti-fade mounting reagent, CITIFLUOR was used (City University, London).…”

Reduced Immunogenicity of Arabidopsis hgl1 Mutant N-Glycans Caused by Altered Accessibility of Xylose and core Fucose Epitopes

“…9 and references cited therein). This structure was hardly detectable in leaves (10) but found in the stem tissue of Arabidopsis (11). Mutants defective in GnTI (such as cgl1 (complex glycan 1) (12) entirely lack complex-type N-glycans characterized by xylose and core fucose residues ( Fig.…”