Abstract
Arabinogalactan-proteins (AGPs) are a family of proteoglycans found in plasma membrane and cell walls of higher plants. As backbones of the carbohydrate moieties, AGPs commonly have beta-3,6-galactans, to which other auxiliary sugars such as L-arabinose (L-Ara), glucuronic acid (GlcA), and 4-O-methyl-GlcA (4-Me-GlcA) are attached. Although a variety of proteins are expected to undergo the arabinogalactan (AG) modification in vivo, the physiological functions of AG moieties remain obscure. In the present study, the structure of carbohydrate moieties of AGPs was altered with fungal alpha-L-arabinofuranosidase (Arafase) and beta-glucuronidase (GlcAase). Recombinant Arafase (rArafase) released L-Ara from AGP from radish roots in vitro. Recombinant GlcAase acted on GlcA and 4-Me-GlcA residues of the AGP in the collaborative manner with rArafase while it failed to act alone. Transgenic Arabidopsis plants expressing the Arafase and GlcAase exhibited higher activities of Arafase and GlcAase than wild-type plants.
Konishi et al., (2008) Carbohydr. Res. 343, 1191-1201
