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

Abstract

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.

Keywords: AEC; AGP; Arabinogalactan proteins; DP; FLA; Fasciclin; GPC; HPAEC-PAD; Jatropha curcas L.; LC; LYSM; LysM; LysM domain-containing proteins; MALLS; MS; MW; N-/O-glycosylation; SPB; TFMS; XLP; Xylogen; anion exchange chromatography; arabinogalactan protein; degree of polymerization; fasciclin-like arabinogalactans; gel permeation chromatography; high pressure anion exchange chromatography with pulsed-amperometric detection; liquid chromatography; mass spectrometry; molecular weight; multi-angel laser light scattering; sodium phosphate buffer; trifluoromethanesulphonic acid; xylogen-like proteins.