Sialic acid-binding dwarf elder four-chain lectin displays nucleic acid N-glycosidase activity

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• 作者：Rosario Iglesias ; Lucí ; a Citores ; J. Miguel Ferreras ; Yol ; a Pé ; rez ; Pilar Jimé ; nez ; Manuel J. Gayoso ; Sjur Olsnes ; Rachele Tamburino ; Antimo Di Maro ; Augusto Parente ; Tomá ; s Girbé
• 关键词：Sambucus ebulus L. ; Agglutinin ; Ribosome-inactivating protein (RIP) ; SEA ; Ricin
• 刊名：Biochimie
• 出版年：2010
• 出版时间：January 2010
• 年：2010
• 卷：92
• 期：1
• 页码：71-80
• 全文大小：1924 K

文摘

Sialic acid-binding dwarf elder agglutinin (SEA) present only in rhizomes of the medicinal plant Sambucus ebulus L., was found to be a tetrameric glycoprotein consisting of two covalently-associated dimers of an enzymic A chain with rRNA N-glycosidase activity (EC 3.2.2.22) linked to a B chain with agglutinin properties. The lectin inhibited protein synthesis by a cell-free system and depurinated ribosomes. Cloning of the corresponding gene and molecular modeling of the deduced amino acid sequence demonstrated that SEA has a three-dimensional structure which resembles that reported for other two tetrameric type 2 RIPs from Sambucus (SNAI and SSA). The lectin agglutinated red blood cells and displayed sugar affinity for sialic acid residues apart from d-galactose, binding to the mucin-producing gut goblet cells. Since sialic acid is present in animal cells, especially in epithelial lining gut cells, but not in plants, SEA could play a role in the defense against insect attack.

The nucleotide sequence reported in this paper has been submitted to the GenBank nucleotide database under accession number AM981401.