title: Molecular characterization of two novel antibacterial peptides inducible upon bacterial challenge in an annelid, the leech Theromyzon tessulatum.
abstract: Two novel antimicrobial peptides named theromacin and theromyzin were isolated and characterized from the coelomic liquid of the leech Theromyzon tessulatum. Theromacin is a 75-amino acid cationic peptide containing 10 cysteine residues arranged in a disulfide array showing no similarities with other known antimicrobial peptides. Theromyzin is an 86-amino acid linear peptide and constitutes the first anionic antimicrobial peptide observed in invertebrates. Both peptides exhibit activity directed against Gram-positive bacteria. Theromacin and theromyzin cDNAs code precursor molecules containing a putative signal sequence directly followed by the mature peptide. The enhancement of theromacin and theromyzin mRNA levels has been observed after blood meal ingestion and upon bacterial challenge. In situ hybridization revealed that both genes are expressed in large fat cells in contact with coelomic cavities. Gene products were immunodetected in large fat cells, in intestinal epithelia, and at the epidermis level. In addition, a rapid release of the peptides into the coelomic liquid was observed after bacterial challenge. The presence of antimicrobial peptide genes in leeches and their expression in a specific tissue functionally resembling the insect fat body provide evidence for the first time of an antibacterial response in a lophotrochozoan comparable to that of holometabola insects.
authors.affiliation: Centre National de la Recherche Scientifique, Laboratoire de Neuroimmunologie UMR 8017, SN3, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Tasiemski
authors.forename: Franck
authors.initials: F
authors.lastname: Vandenbulcke
authors.forename: Guillaume
authors.initials: G
authors.lastname: Mitta
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lemoine
authors.forename: Christophe
authors.initials: C
authors.lastname: Lefebvre
authors.forename: Pierre-Eric
authors.initials: PE
authors.lastname: Sautière
authors.forename: Michel
authors.initials: M
authors.lastname: Salzet
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D006094:Gram-Positive Bacteria / Q000187:drug effects; D007150:Immunohistochemistry; D007865:Leeches / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010452:Peptide Biosynthesis; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D018076:DNA, Complementary; D010455:Peptides; D012333:RNA, Messenger; C490018:theromacin, leech; C490019:theromyzin, leech