title: cDNA cloning and characterization of a rhamnose-binding lectin SUL-I from the toxopneustid sea urchin Toxopneustes pileolus venom.
abstract: The globiferous pedicellariae of the venomous sea urchin Toxopneustes pileolus contain several biologically active proteins. Among these, a galactose-binding lectin SUL-I isolated from the venom in the large globiferous pedicellariae shows several activities such as mitogenic, chemotactic, and cytotoxic activities through binding to the carbohydrate chains on the cells. We cloned cDNA encoding SUL-I by reverse transcription-PCR using the degenerate primers designed on the basis of the N-terminal amino acid sequence of the protein and expressed the recombinant SUL-I (rSUL-I) in Escherichia coli cells. The SUL-I gene contains an open reading frame of 927 nucleotides corresponding to 308 amino acid residues, including 24 residues of a putative signal sequence. The mature protein with 284 residues is composed of three homologous regions, each showing similarity with the carbohydrate-recognition domains of the rhamnose-binding lectins, which have been mostly found in fish eggs. While rSUL-I exhibited binding activity for several galactose-related sugars, the highest affinity was found for l-rhamnose among carbohydrates tested, confirming that SUL-I is a rhamnose-binding lectin. rSUL-I also showed hemagglutinating activity toward rabbit erythrocytes, indicating the existence of more than one carbohydrate-binding site to cross-link the carbohydrate chains on the cell surface, which may be closely related to its biological activities.
authors.affiliation: Biomolecular Chemistry Laboratory, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan. Electronic address: thata@nagasaki-u.ac.jp.
authors.forename: Tomomitsu
authors.initials: T
authors.lastname: Hatakeyama
authors.affiliation: Biomolecular Chemistry Laboratory, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Ichise
authors.affiliation: Biomolecular Chemistry Laboratory, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Yonekura
authors.affiliation: Biomolecular Chemistry Laboratory, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Unno
authors.affiliation: Biomolecular Chemistry Laboratory, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan.
authors.forename: Shuichiro
authors.initials: S
authors.lastname: Goda
authors.affiliation: Division of Environmental Symbiosis, Graduate School of Integrated Arts and Sciences, Tokushima University, Tokushima 770-8502, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Nakagawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D004912:Erythrocytes / Q000187:drug effects*; D037161:Galectins / Q000494:pharmacology*; D006384:Hemagglutination / Q000187:drug effects*; D008387:Marine Toxins / Q000737:chemistry* / Q000494:pharmacology; D008969:Molecular Sequence Data; D011817:Rabbits; D012210:Rhamnose / Q000378:metabolism*; D012617:Sea Urchins / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D014688:Venoms / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D037161:Galectins; D008387:Marine Toxins; D014688:Venoms; D012210:Rhamnose
keywords: Carbohydrate-binding; Lectin; Rhamnose; Sea urchin; Toxopneustes pileolus; cDNA cloning