title: A lectin from the mussel Mytilus galloprovincialis has a highly novel primary structure and induces glycan-mediated cytotoxicity of globotriaosylceramide-expressing lymphoma cells.
abstract: A novel lectin structure was found for a 17-kDa α-D-galactose-binding lectin (termed "MytiLec") isolated from the Mediterranean mussel, Mytilus galloprovincialis. The complete primary structure of the lectin was determined by Edman degradation and mass spectrometric analysis. MytiLec was found to consist of 149 amino acids with a total molecular mass of 16,812.59 Da by Fourier transform-ion cyclotron resonance mass spectrometry, in good agreement with the calculated value of 16,823.22 Da. MytiLec had an N terminus of acetylthreonine and a primary structure that was highly novel in comparison with those of all known lectins in the structure database. The polypeptide structure consisted of three tandem-repeat domains of ∼50 amino acids each having 45-52% homology with each other. Frontal affinity chromatography technology indicated that MytiLec bound specifically to globotriose (Gb3; Galα1-4Galβ1-4Glc), the epitope of globotriaosylceramide. MytiLec showed a dose-dependent cytotoxic effect on human Burkitt lymphoma Raji cells (which have high surface expression of Gb3) but had no such effect on erythroleukemia K562 cells (which do not express Gb3). The cytotoxic effect of MytiLec was specifically blocked by the co-presence of an α-galactoside. MytiLec treatment of Raji cells caused increased binding of anti-annexin V antibody and incorporation of propidium iodide, which are indicators of cell membrane inversion and perforation. MytiLec is the first reported lectin having a primary structure with the highly novel triple tandem-repeat domain and showing transduction of apoptotic signaling against Burkitt lymphoma cells by interaction with a glycosphingolipid-enriched microdomain containing Gb3.
authors.affiliation: Laboratory of Glycobiology and Marine Biochemistry, Department of Life and Environmental System Science, Graduate School of NanoBio Sciences, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Fujii
authors.forename: Naoshi
authors.initials: N
authors.lastname: Dohmae
authors.forename: Koji
authors.initials: K
authors.lastname: Takio
authors.forename: Sarkar M A
authors.initials: SM
authors.lastname: Kawsar
authors.forename: Ryo
authors.initials: R
authors.lastname: Matsumoto
authors.forename: Imtiaj
authors.initials: I
authors.lastname: Hasan
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Koide
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kanaly
authors.forename: Hidetaro
authors.initials: H
authors.lastname: Yasumitsu
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Shigeki
authors.initials: S
authors.lastname: Sugawara
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hosono
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nitta
authors.forename: Jiharu
authors.initials: J
authors.lastname: Hamako
authors.forename: Taei
authors.initials: T
authors.lastname: Matsui
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ozeki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002051:Burkitt Lymphoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D045744:Cell Line, Tumor; D006801:Humans; D020014:K562 Cells; D037102:Lectins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D008969:Molecular Sequence Data; D049878:Mytilus / Q000737:chemistry / Q000378:metabolism*; D010449:Peptide Mapping; D011134:Polysaccharides / Q000378:metabolism*; D016415:Sequence Alignment; D014281:Trihexosylceramides / Q000235:genetics / Q000378:metabolism*
chemical_list: D037102:Lectins; D011134:Polysaccharides; D014281:Trihexosylceramides; C018549:globotriaosylceramide