Characterization and cDNA cloning of monomeric lectins that correspond to the B-chain of a type 2 ribosome-inactivating protein from the bark of Japanese elderberry (Sambucus sieboldiana)

Maria Angeles Rojo, Hanae Kaku, Naoko Ishii-Minami, Eiichi Minami, Misa Yato, Shigeru Hisajima, Takeshi Yamaguchi, Naoto Shibuya

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Abstract

Two monomeric lectins, SSA-b-3 and SSA-b-4, were purified from the bark tissue of Japanese elderberry, Sambucus sieboldiana. SDS-PAGE of the purified lectins showed the presence of single bands of 35 and 33 kDa for SSA-b-3 and SSA-b-4, respectively, irrespective of the presence of reducing agent. MS analysis as well as gel filtration of these lectins indicated that they exist mostly as monomeric lectins. Analysis of the N-terminal amino acid sequences of SSA-b-3 and SSA-b-4 yielded an identical sequence, indicating their close structural relationship. Four cDNA clones with extensive homology were obtained from the bark cDNA library and indicated to encode SSA-b-3 or SSA-b-4 from the comparison with the N-terminal sequences of these lectins. These clones were classified into two groups, three for SSA-b-3 and one for SSA-b-4, based on the predicted isoelectric points. The amino acid sequences of the encoded polypeptides were almost identical with the B-chain of a type 2 ribosome-inactivating protein from the same bark tissue, sieboldin-b, except for the absence of a small peptide containing a cystein residue, which is critical for the heteromeric dimerization with an A-subunit. Carbohydrate binding specificity and biological activity of these lectins are also reported.

Original languageEnglish
Pages (from-to)509-516
Number of pages8
JournalJournal of Biochemistry
Volume135
Issue number4
DOIs
Publication statusPublished - 1 Apr 2004

Keywords

  • Bark
  • Elderberry
  • Lectin
  • Ribosome-inactivating protein
  • Sambucus sieboldiana
  • cDNA

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