title: Characterization of a novel piscidin-like antimicrobial peptide from Pseudosciaena crocea and its immune response to Cryptocaryon irritans.
abstract: Piscidins, important components of the innate (nonspecific) immunity system in fish, have potent, broad-spectrum antimicrobial and antiparasitic activities. In this study, we reported a novel antimicrobial cationic peptide from Pseudosciaena crocea. Although this peptide exhibited a genomic (3 exons and 2 introns) and propeptide (signal peptide, mature peptide and prodomain) organization, conserved signal peptide (22 amino acids) and consensus motif I-X5-H-X4-I-H identical to the reported fish piscidins, Pc-pis showed a relatively low overall conservation with other known piscidins, which was obviously embodied in the amino acid composition of the peptide. Pc-pis is strikingly rich in glycine residues (27.3%), which disrupted the amphipathic structure of the peptide. Relative quantitative real-time PCR revealed that Pc-pis is a typically gill-expressed peptide. The sequence analysis, structural features and tissue distribution suggested that Pc-pis was genetically related to the piscidins family and might be a novel piscidin-like antimicrobial peptide. Quantitative PCR analysis revealed that the expression of Pc-pis in the spleen, head-kidney, liver, intestine, skin and gill could be regulated during Cryptocaryon irritans infection and post C. irritans falling off, implicating a role for Pc-pis in immune defense against C. irritans and secondary bacterial infections. Synthetic Pc-pis exhibited broad-spectrum activity against bacteria, fungi and C. irritans in parasitic stages. These results provided the first evidence of piscidins antiparasitic activity against marine fish ectoparasites C. irritants trophonts and further indicated that Pc-pis might be an important component of the P. crocea innate immune system against C. irritans and secondary bacterial infections. Thus, these data provided new insights into P. crocea innate immunity against external protozoan parasite and microbial infections and facilitate the evaluation of Pc-pis as a therapeutic agent against pathogen invasion.
authors.affiliation: College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian 361005, China.
authors.forename: Su-Fang
authors.initials: SF
authors.lastname: Niu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Jin
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Qiao
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.forename: Yong
authors.initials: Y
authors.lastname: Mao
authors.forename: Yong-Quan
authors.initials: YQ
authors.lastname: Su
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001234:Aspergillus niger / Q000502:physiology; D001483:Base Sequence; D002176:Candida albicans / Q000502:physiology; D016798:Ciliophora / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D016770:Ciliophora Infections / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005393:Fish Diseases / Q000276:immunology* / Q000469:parasitology; D005786:Gene Expression Regulation; D020459:Genes, rRNA; D006090:Gram-Negative Bacteria / Q000502:physiology; D006094:Gram-Positive Bacteria / Q000502:physiology; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D016415:Sequence Alignment / Q000662:veterinary
chemical_list: D023181:Antimicrobial Cationic Peptides; D018076:DNA, Complementary; D012333:RNA, Messenger; D016053:RNA, Protozoan
keywords: Biological activity; Cryptocaryon irritans; Immune response; Novel piscidin-like; Pseudosciaena crocea