Arabinogalactan protein cluster from Jatropha curcas seed embryo contains fasciclin, xylogen and LysM proteins

An non-GPI-anchored AGP cluster (Y2) was isolated from the seeds of Jatropha curcas L. (Euphorbiaceae) composed of 4.8% polypeptides (mainly Ala, Ser, Gly, Hyp, Glu) and a carbohydrate moiety composed of Gal, Ara, GlcA, Rha, Man and GlcN. Besides the typical structural features of arabinogalactan proteins, typical N-glycan linker of the complex type (GlcNAc4Man3Gal2Fuc1Xyl1) were identified. O-glycosylation occurred mainly via Hyp and to a lesser extent via Thr and Ser. N-glycans from the complex type, carrying at the innermost GlcNAc at position O-3 one α-Fuc-residue, were also present. MS analysis of the tryptic digest assigned peptides of three major protein groups: fasciclin-like arabinogalactan proteins, xylogen-like proteins and LysM domain-containing proteins. They could not be separated further and it is indicated that various homologous protein forms co-exist. Histological investigation of J. curcas seeds revealed the presence of AGPs in the vessels of cotyledons and in the procambium ring of the embryo.

Proteoglycans from Boswellia serrata Roxb. and B. carteri Birdw. and identification of a proteolytic plant basic secretory protein

Water-soluble high molecular weight compounds were isolated in yields of 21-22% from the oleogum of Boswellia serrata and B. carteri. Using anion exchange chromatography and gel permeation chromatography, different proteoglycans were purified and characterized, leading to four principally different groups: (i) Hyp-/Ser-rich extensins with O-glycosidic attached arabinan side chains; (ii) Modified extensins, with arabinogalactosylated side chains containing GlA and 4-O-Me-GlcA; (iii) Glycoproteins with N-glycosidic side chains containing higher amounts of Fuc, Man and GluNH(2,) featuring a 200 kD metalloproteinase that has been de novo sequenced and is described for the first time; (iv) Type II arabinogalactans-proteins. Significant differences between the gums from the two species were observed in the protein content (6% vs 22%), offering the possibility of a quick differentiation of gums from both species for analytical quality control. The data also offer an insight into the plant response towards wound-closing by the formation of extensin and AGP-containing gum.