title: Isolation of novel prototype galectins from the marine ball sponge Cinachyrella sp. guided by their modulatory activity on mammalian glutamate-gated ion channels.
abstract: Here we report the bioactivity-guided isolation of novel galectins from the marine sponge Cinachyrella sp., collected from Iriomote Island, Japan. The lectin proteins, which we refer to as the Cinachyrella galectins (CchGs), were identified as the active principles in an aqueous sponge extract that modulated the function of mammalian ionotropic glutamate receptors. Aggregation of rabbit erythrocytes by CchGs was competed most effectively by galactosides but not mannose, a profile characteristic of members of the galectin family of oligosaccharide-binding proteins. The lectin activity was remarkably stable, with only a modest loss in hemagglutination after exposure of the protein to 100°C for 1 h, and showed little sensitivity to calcium concentration. CchG-1 and -2 appeared as 16 and 18 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively, whereas matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry indicated broad ion clusters centered at 16,216 and 16,423, respectively. The amino acid sequences of the CchGs were deduced using a combination of Edman degradation and cDNA cloning and revealed that the proteins were distant orthologs of animal prototype galectins and that multiple isolectins comprised the CchGs. One of the isolectins was expressed as a recombinant protein and exhibited physico-chemical and biological properties comparable with those of the natural lectins. The biochemical properties of the CchGs as well as their unexpected activity on mammalian excitatory amino acid receptors suggest that further analysis of these new members of the galectin family will yield further glycobiological and neurophysiological insights.
authors.affiliation: Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho Hakodate, Hokkaido 041-8611, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Ueda
authors.forename: Yuka
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Caleb M
authors.initials: CM
authors.lastname: Smith
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Copits
authors.forename: Akira
authors.initials: A
authors.lastname: Inoue
authors.forename: Takao
authors.initials: T
authors.lastname: Ojima
authors.forename: Satoko
authors.initials: S
authors.lastname: Matsunaga
authors.forename: Geoffrey T
authors.initials: GT
authors.lastname: Swanson
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Sakai
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D005697:Galactosides / Q000276:immunology; D037161:Galectins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*; D057809:HEK293 Cells; D006384:Hemagglutination; D006801:Humans; D008297:Male; D008358:Mannose / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D011161:Porifera / Q000737:chemistry*; D011485:Protein Binding; D011817:Rabbits; D018091:Receptors, AMPA / Q000187:drug effects*; D018092:Kainic Acid Receptors / Q000187:drug effects*
chemical_list: D002118:Calcium; D005697:Galactosides; D037161:Galectins; D008358:Mannose; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors