title: AIP56: a novel bacterial apoptogenic toxin.
abstract: Photobacterium damselae subsp. piscicida (Phdp) is a Gram-negative pathogen agent of an important fish septicemia. The key virulence factor of Phdp is the plasmid-encoded exotoxin AIP56, which is secreted by exponentially growing pathogenic strains. AIP56 has 520 amino acids including an N-terminal cleavable signal peptide of 23 amino acid residues, two cysteine residues and a zinc-binding region signature HEXXH that is typical of most zinc metallopeptidases. AIP56 induces in vitro and in vivo selective apoptosis of fish macrophages and neutrophils through a caspase-3 dependent mechanism that also involves caspase-8 and -9. In vivo, the AIP56-induced phagocyte apoptosis progresses to secondary necrosis with release of cytotoxic phagocyte molecules including neutrophil elastase. Fish injected with recombinant AIP56 die with a pathology similar to that seen in the natural infection.
authors: IBMC-Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, 823. 4150-180 Porto, Portugal. mtsilva@ibmc.up.pt
authors: Manuel T
authors: MT
authors: Silva
authors: Nuno M S
authors: NM
authors: Dos Santos
authors: Ana
authors: A
authors: do Vale
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001427:Bacterial Toxins / Q000633:toxicity*; D006801:Humans; D008264:Macrophages / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects; D010776:Photobacterium / Q000472:pathogenicity*; D037521:Virulence Factors / Q000633:toxicity
chemical_list: D001427:Bacterial Toxins; D037521:Virulence Factors