Plants Get Hyp to O-Glycosylation

摘要

The two most abundant natural organic polymers on Earth are cellulose and chitin, characterized by long chains of carbohydrates that bear a specific type of sugar linkage called O-glycosylation. This type of linkage also occurs between polysac-charides (glycans) and proteins and glycans and lipids, yielding glycoconjugates that are well known to function in cell recognition processes (1). On page 1401 in this issue, Velasquez et al. (2) explore a specific type of O-glycosylation for plant cell wall structural proteins and connect this modification to root hair growth. Two types of sugar linkages predominate in glycoproteins: N-linkage of glycans to asparagine residues, and O-linkages, which are structurally more complex and most commonly connect glycans to the hydroxyl group of serine or threonine residues. Glycans, however, can also be attached to lysine or proline (Pro) if these amino acids are first hydroxylated. This type of O-glycosylation is addressed by Velasquez et al.