title: Differences in amino acid sequences of mistletoe lectin I and III B-subunits determining carbohydrate binding specificity.
abstract: Toxic lectins of European mistletoe Viscum album L.--MLI (viscumin), MLII and MLIII--are present in water extracts of this plant. Earlier we have cloned the full-length gene of MLIII precursor [A.G. Tonevitsky, I.I. Agapov, I.B. Pevzner, N.V. Maluchenko, M.M. Mojsenovich, U. Pfueller, M.P. Kirpichnikov, (2004) Biochemistry (Mosc.), 69 (6), 790-800, in press]. Here for the first time we report the cloning and expression in Escherichia coli cells of MLIII gene fragment encoding the carbohydrate-binding subunit. We have proved with our panel of monoclonal antibodies against ML toxins that the cloned fragment encoded MLIII B-subunit. The immunochemical and sugar-binding activities of renatured recombinant MLIII B-subunit were demonstrated in ELISA and ELLA, respectively. The comparative analysis of amino acid sequences of the cloned rMLIIIB and the B-subunits of other type II RIPs--MLI, ricin, abrin and nigrin b--was performed, revealing the main differences in primary structure of MLI and MLIII B-chains, which could determine their sugar specificity. The antigenicity analysis of MLI and MLIII B-subunits showed one epitope 25RDDDFRDGNQ34 in MLIB that is absent in MLIIIB sequence. The role of the toxic lectins and their subunits in immunological properties of mistletoe extracts is discussed.
authors.affiliation: Biological Department, MV Lomonosov Moscow State University, Vorobyevy Gory, Moscow 119899, Russia.
authors.forename: Irina B
authors.initials: IB
authors.lastname: Pevzner
authors.forename: Igor I
authors.initials: II
authors.lastname: Agapov
authors.forename: Hideaki
authors.initials: H
authors.lastname: Niwa
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Maluchenko
authors.forename: Mikhail M
authors.initials: MM
authors.lastname: Moisenovich
authors.forename: Uwe
authors.initials: U
authors.lastname: Pfüller
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Tonevitsky
mesh_terms: D000276:Adjuvants, Immunologic; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D050260:Carbohydrate Metabolism; D003001:Cloning, Molecular; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D004926:Escherichia coli / Q000378:metabolism; D014784:Mistletoe / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D037121:Plant Lectins / Q000235:genetics* / Q000378:metabolism*; D028321:Plant Preparations / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D054790:Ribosome Inactivating Proteins, Type 2; D012276:Ricin / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014118:Toxins, Biological / Q000235:genetics / Q000378:metabolism; D028182:Viscum album / Q000737:chemistry
chemical_list: D000276:Adjuvants, Immunologic; D000911:Antibodies, Monoclonal; D000939:Epitopes; D037121:Plant Lectins; D028321:Plant Preparations; D010940:Plant Proteins; D021122:Protein Subunits; D011994:Recombinant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological; C009674:ribosome inactivating protein, Viscum; D012276:Ricin