Abstract
Protein glycosylation is an essential co- and post-translational modification of secretory and membrane proteins in all eukaryotes. The initial steps of N-glycosylation and N-glycan processing are highly conserved between plants, mammals and yeast. In contrast, late N-glycan maturation steps in the Golgi differ significantly in plants giving rise to complex N-glycans with β1,2-linked xylose, core α1,3-linked fucose and Lewis A-type structures. While the essential role of N-glycan modifications on distinct mammalian glycoproteins is already well documented, we have only begun to decipher the biological function of this ubiquitous protein modification in different plant species. In this review, I focus on the biosynthesis and function of different protein N-linked glycans in plants. Special emphasis is given on glycan-mediated quality control processes in the ER and on the biological role of characteristic complex N-glycan structures.
Highlights
Asparagine (N)-linked glycosylation (ALG) of proteins is the most common co- and post-translational modification of proteins entering the secretory pathway
This review focuses on recent findings concerning the biological role of oligomannosidic and complex N-glycans in different plants
The N-glycan processing pathway in plants is quite well understood and all enzymatic steps leading to the formation of the known N-glycan structures have been investigated
Summary
Asparagine (N)-linked glycosylation (ALG) of proteins is the most common co- and post-translational modification of proteins entering the secretory pathway. The molecular mechanisms for terminal α1,6-linked Man formation and recognition are in principle conserved between eukaryotic species, the N-glycans of plant ERAD substrates display considerable amounts of mono-glucosylated structures (Hüttner, Veit, Vavra, Schoberer, Dicker, et al 2014; Hüttner, Veit, Vavra, Schoberer, Liebminger, et al 2014) (Figure 3) The significance of this difference is unclear, but it is plausible that the CNX/calreticulin cycle and the ERAD machinery interact very closely in plants. A glycoproteomics study from etiolated A. thaliana hypocotyls identified a single glycoprotein with a mono-antennary Lewis A-type N-glycan at one of its N-glycosylation sites (Zhang et al 2011) The function of this cell wall glycoprotein with homology to blue copper binding proteins has not been studied and the biological relevance of Lewis A structures on plant complex N-glycans is still obscure. Future genetic and biochemical studies should aim to identify this unknown glycoprotein with a functional complex N-glycan structure in plants
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
