Isolation and molecular cloning of a novel type 2 ribosome-inactivating protein with an inactive B chain from elderberry (Sambucus nigra) bark.
One of the predominant proteins in the bark of elderberry (Sambucus nigra) has been identified as a novel type 2 ribosome-inactivating protein that exhibits a normal RNA N-glycosidase activity, but is devoid of carbohydrate binding activity. Sequence analysis of the corresponding cDNA clones revealed a striking homology to the previously cloned bark lectins from elderberry, suggesting that the new protein is a lectin-related protein. Molecular modeling of the protein confirmed that its A chain is fully active, whereas its B chain contains two functionally inactive carbohydrate-binding sites. These findings not only demonstrate for the first time the occurrence of a type 2 ribosome-inactivating protein with an inactive B chain, but also offer interesting perspectives for the synthesis of immunotoxins with an improved selectivity.
Van Damme
E J
EJ
Laboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven, Willem de Croylaan 42, 3001 Leuven, Belgium.
Barre
A
A
Rougé
P
P
Van Leuven
F
F
Peumans
W J
WJ
D000595:Amino Acid Sequence; D050260:Carbohydrate Metabolism; D018744:DNA, Plant / Q000737:chemistry; D004912:Erythrocytes / Q000187:drug effects; D006384:Hemagglutination; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D010449:Peptide Mapping; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D054790:Ribosome Inactivating Proteins, Type 2
D018744:DNA, Plant; D010940:Plant Proteins; D011500:Protein Synthesis Inhibitors; D054790:Ribosome Inactivating Proteins, Type 2; D009699:N-Glycosyl Hydrolases