Molecular cloning of the bark and seed lectins from the Japanese pagoda tree (Sophora japonica) |
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Authors: | Van Damme Els J.M. Barre Annick Rougé Pierre Peumans Willy J. |
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Affiliation: | (1) Laboratory for Phytopathology and Plant Protection, Katholieke Universiteit Leuven, Willem de Croylaan 42, 3001 Leuven, Belgium;(2) Institut de Pharmacologie et Biologie Structurale, UPR CNRS 9062, Université Paul Sabatier, 35 Chemin des Maraîchers, 31062 Toulouse Cedex, France |
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Abstract: | cDNA clones encoding the bark and seed lectins from Sophora japonica were isolated and their sequences analyzed. Screening of a cDNA library constructed from polyA RNA isolated from the bark resulted in the isolation of three different lectin cDNA clones. The first clone encodes the GalNAc-specific bark lectin which was originally described by Hankins et al. whereas the other clones encode the two isoforms of the mannose/glucose-specific lectin reported by Ueno et al.. Molecular cloning of the seed lectin genes revealed that Sophora seeds contain only a GalNAc-specific lectin which is highly homologous to though not identical with the GalNAc-specific lectin from the bark. All lectin polypeptides are translated from mRNAs of ca. 1.3 kb encoding a precursor carrying a signal peptide. In the case of the mannose/glucose-specific bark lectins this precursor is post-translationally processed in two smaller peptides. Alignment of the deduced amino acid sequences of the different clones revealed striking sequence similarities between the mannose/glucose-binding and the GalNAc-specific lectins. Furthermore, there was a high degree of sequence homology with other legume lectins which allowed molecular modelling of the Sophora lectins using the coordinates of the Pisum sativum, Lathyrus ochrus and Erythrina corallodendron lectins. |
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Keywords: | bark proteins cDNA cloning lectin Sophora japonica |
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