抄録
Hydroxyproline-rich glycoproteins (HRGPs), comprising extensins, proline-rich proteins (PRPs) and arabinogalactan proteins (AGPs) are abundant structural components unique to green algae and green plants where they contribute to cell wall networks and the plasma membrane glycocalyx. HRGPs are extended macromolecules consisting of small repetitive peptide and glycopeptide motifs that form peptide modules and glycomodules of functional significance, as in "mix and match" mode they define the molecular properties of the overall macromolecule. The glycomodules result from a combination of posttranslational modifications unique to plants, namely proline hydroxylation/glycosylation that leads either to short arabinooligosaccharide or larger arabinogalactan polysaccharide added to the hydroxyproline residues. The precise oligosaccharides or polysaccharide addition is driven by a sequence-dependent O-Hyp glycosylation code recently elucidated in this laboratory: contiguous Hyp residues direct the addition of homo-arabinooligosaccharides to Hyp, while clustered non-contiguous Hyp residues direct the addition of a complex arabinogalactan heteropolysaccharide often containing glucuronic acid and rhamnose in addition to arabinose and galactose. This advance in combination with synthetic gene technology now allows us to design novel glycoproteins, arabinogalactan-proteins and gums whose properties can be optimised to provide new fibres, filters, films, pharmaceuticals and foods.
