Sialic acid-binding dwarf elder four-chain lectin displays nucleic acid N-glycosidase activity |
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Authors: | Rosario Iglesias Lucía Citores J Miguel Ferreras Yolanda Pérez Pilar Jiménez Manuel J Gayoso Sjur Olsnes Rachele Tamburino Antimo Di Maro Augusto Parente Tomás Girbés |
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Institution: | 1. Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Valladolid, E-47005 Valladolid, Spain;2. Nutrición y Bromatología, Facultad de Medicina and CINAD, Universidad de Valladolid, E-47005 Valladolid, Spain;3. Departamento de Biología Celular, Histología y Farmacología, Facultad de Medicina, Universidad de Valladolid, E-47005 Valladolid, Spain;4. Centre for Cancer Biomedicine, Institute for Cancer Research, Rikshospitalet-Radiumhospitalet Medical Centre, Montebello, University of Oslo, 0310 Oslo, Norway;5. Dipartimento di Scienze della Vita, Seconda Università di Napoli, 81100 Caserta, Italy |
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Abstract: | 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. |
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Keywords: | Sambucus ebulus L Agglutinin Ribosome-inactivating protein (RIP) SEA Ricin |
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