XVI International Botanical Congess

The repetitive glycopeptide modules that characterize HRGPs confer molecular properties which depend on the arrangement of the glycosyl substituents along the polypeptide backbone.What determines the arrangement? The Hyp-contiguity Hypothesis correlates arabinosylation with Hyp contiguity and suggests that clustered noncontiguous Hyp residues direct arabinogalactan polysaccharide addition in AGPs. We tested these predictions by designing repetitive synthetic HRGP genes containing only one putative glycosylation motif.The first gene tested encoded a glycopeptide module that was a predicted site of polysaccharide addition in AGPs. Transformation of tobacco cultures with the gene fused to green fluorescent protein led to the ready isolation of the gene product from culture medium. The gene product was an AGP with an arabinogalactan attached to each Hyp residue.