title: A Transmissible Plasmid-Borne Pathogenicity Island Confers Piscibactin Biosynthesis in the Fish Pathogen Photobacterium damselae subsp. piscicida.
abstract: The fish pathogen Photobacterium damselae subsp. piscicida produces the siderophore piscibactin. A gene cluster that resembles the Yersinia high-pathogenicity island (HPI) encodes piscibactin biosynthesis. Here, we report that this HPI-like cluster is part of a hitherto-uncharacterized 68-kb plasmid dubbed pPHDP70. This plasmid lacks homologs of genes that mediate conjugation, but we found that it could be transferred at low frequencies from P. damselae subsp. piscicida to a mollusk pathogenic Vibrio alginolyticus strain and to other Gram-negative bacteria, likely dependent on the conjugative functions of the coresident plasmid pPHDP60. Following its conjugative transfer, pPHDP70 restored the capacity of a vibrioferrin mutant of V. alginolyticus to grow under low-iron conditions, and piscibactin became detectable in its supernatant. Thus, pPHDP70 appears to harbor all the genes required for piscibactin biosynthesis and transport. P. damselae subsp. piscicida strains cured of pPHDP70 no longer produced piscibactin, had impaired growth under iron-limited conditions, and exhibited markedly decreased virulence in fish. Collectively, our findings highlight the importance of pPHDP70, with its capacity for piscibactin-mediated iron acquisition, in the virulence of P. damselae subsp. piscicida. Horizontal transmission of this plasmid-borne piscibactin synthesis gene cluster in the marine environment may facilitate the emergence of new pathogens.
authors.affiliation: Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain cr.osorio@usc.es.
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Osorio
authors.affiliation: Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Amable J
authors.initials: AJ
authors.lastname: Rivas
authors.affiliation: Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Balado
authors.affiliation: Departamento de Química Fundamental, Facultade de Ciencias and Centro de Investigacións Científicas Avanzadas, Universidade da Coruña, A Coruña, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Fuentes-Monteverde
authors.affiliation: Departamento de Química Fundamental, Facultade de Ciencias and Centro de Investigacións Científicas Avanzadas, Universidade da Coruña, A Coruña, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Rodríguez
authors.affiliation: Departamento de Química Fundamental, Facultade de Ciencias and Centro de Investigacións Científicas Avanzadas, Universidade da Coruña, A Coruña, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Jiménez
authors.affiliation: Departamento de Microbioloxía e Parasitoloxía, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
authors.forename: Manuel L
authors.initials: ML
authors.lastname: Lemos
authors.affiliation: Division of Infectious Diseases, Brigham and Women's Hospital and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Waldor
mesh_terms: D000818:Animals; D005393:Fish Diseases / Q000382:microbiology*; D022761:Gene Transfer, Horizontal; D044404:Genomic Islands; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D010776:Photobacterium / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D017262:Siderophores / Q000096:biosynthesis*; D014774:Virulence
chemical_list: D017262:Siderophores; D007501:Iron