Isolation, cDNA cloning, biological properties, and carbohydrate binding specificity of sieboldin-b, a type II ribosome-inactivating protein from the bark of Japanese elderberry (Sambucus sieboldiana).
A type II ribosome-inactivating protein (RIP) was isolated from the bark tissue of Japanese elderberry (Sambucus sieboldiana) and named sieboldin-b. Sieboldin-b is a heterodimeric protein consisting of 27- and 33-kDa subunits and showed strong ribosome-inactivating activity in vitro but did not show in vivo toxicity. The amino acid sequence of sieboldin-b deduced from the structure of the cDNA showed that both subunits of sieboldin-b are encoded on a single precursor polypeptide. Sieboldin-b has a structure homologous with the Neu5Ac(alpha 2-6)Gal/GalNAc-specific bark lectin from S. sieboldiana (SSA) and also typical type II RIPs such as ricin and abrin. Detailed analyses of carbohydrate binding properties of sieboldin-b revealed that sieboldin-b binds to Gal/GalNAc, similar to ricin/abrin, in spite of its highly homologous structure with SSA. The biological properties of these toxins/lectins are compared, and the possible explanation for such diversity is discussed.
Rojo
M A
MA
Department of Biotechnology, National Institute of Agrobiological Resources, Ibaraki, Japan.
Yato
M
M
Ishii-Minami
N
N
Minami
E
E
Kaku
H
H
Citores
L
L
Girbés
T
T
Shibuya
N
N
D000595:Amino Acid Sequence; D050260:Carbohydrate Metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D017343:Genes, Plant; D006367:HeLa Cells; D006801:Humans; D037102:Lectins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009699:N-Glycosyl Hydrolases / Q000235:genetics*; D037121:Plant Lectins; D010944:Plants / Q000235:genetics; D011500:Protein Synthesis Inhibitors; D018749:RNA, Plant; D054788:Ribosome Inactivating Proteins
D018076:DNA, Complementary; D037102:Lectins; D037121:Plant Lectins; D011500:Protein Synthesis Inhibitors; D018749:RNA, Plant; C105919:sieboldin b; D009699:N-Glycosyl Hydrolases; D054788:Ribosome Inactivating Proteins