title: Emergence and disappearance of an immune molecule, an antimicrobial lectin, in basal metazoa. A tachylectin-related protein in the sponge Suberites domuncula.
abstract: Sponges (phylum Porifera) represent the evolutionarily oldest metazoans that comprise already a complex immune system and are related to the crown taxa of the protostomians and the deuterostomians. Here, we demonstrate the existence of a tachylectin-related protein in the demosponge Suberites domuncula, termed Suberites lectin. The MAPK pathway was activated in response to lipopolysaccharide treatment of the three-dimensional cell aggregates, the primmorphs; this process was abolished by the monosaccharide D-GlcNAc. The cDNA encoding the S. domuncula lectin was identified and cloned; it comprises 238 amino acids (26 kDa) in the open reading frame. The deduced protein has one potential transmembrane region, three characteristic Cys residues, and six internal tandem repeats; it shares the highest sequence similarity with lectins from the horseshoe crab Tachypleus trunculus. The steady-state level of expression of the Suberites lectin rises in primmorphs in response to lipopolysaccharide, an effect that was prevented by co-incubation with D-GlcNAc. The natural sponge lectin was purified by affinity chromatography; it has a size of 27 kDa and displays antibacterial activity against the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus. The putative protein, deduced from the cloned gene, is identical/similar to the purified natural protein, as demonstrated by immunological cross-reactivity with specific antibodies. We conclude that the S. domuncula lectin acts as an antibacterial molecule involved in immune defense against bacterial invaders.
authors.affiliation: Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Universität Mainz, Duesbergweg 6, D-55099 Mainz, Germany.
authors.forename: Heinz C
authors.initials: HC
authors.lastname: Schröder
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ushijima
authors.forename: Anatoli
authors.initials: A
authors.lastname: Krasko
authors.forename: Vera
authors.initials: V
authors.lastname: Gamulin
authors.forename: Narsinh L
authors.initials: NL
authors.lastname: Thakur
authors.forename: Barbel
authors.initials: B
authors.lastname: Diehl-Seifert
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Müller
authors.forename: Werner E G
authors.initials: WE
authors.lastname: Müller
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D015152:Blotting, Northern; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002845:Chromatography; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003545:Cysteine / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000378:metabolism; D015723:Gene Library; D037102:Lectins / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D011161:Porifera / Q000276:immunology* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D003432:Cross-Linking Reagents; D018076:DNA, Complementary; D037102:Lectins; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D012313:RNA; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D003545:Cysteine; D000117:Acetylglucosamine