The opportunistic marine pathogen Vibrio parahaemolyticus becomes virulent by acquiring a plasmid that expresses a deadly toxin

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 112; no. 34; pp. 10798 - 10803
• Main Authors: Lee, Chung-Te, Chen, I-Tung, Yang, Yi-Ting, Ko, Tzu-Ping, Huang, Yun-Tzu, Huang, Jiun-Yan, Huang, Ming-Fen, Lin, Shin-Jen, Chen, Chien-Yu, Lin, Shih-Shun, Lin, Shih-Shuen, Lightner, Donald V, Wang, Han-Ching, Wang, Andrew H-J, Wang, Hao-Ching, Hor, Lien-I, Lo, Chu-Fang
• Format: Journal Article
• Language: English
• Published: United States National Acad Sciences 25-08-2015; National Academy of Sciences
• Subjects: Animals; Bacillus; Bacterial Proteins - genetics; Bacterial Proteins - isolation & purification; Bacterial Toxins - genetics; Bacterial Toxins - isolation & purification; Biological Sciences; Conjugation, Genetic; Crystal structure; Decapoda; DNA, Bacterial - genetics; Gangrene; Genes, Bacterial; Models, Molecular; Molecular Sequence Data; Open Reading Frames - genetics; Penaeidae - microbiology; Photorhabdus; Plasmids; Plasmids - genetics; Plasmids - metabolism; Porins - chemistry; Protein Conformation; Proteins; Sequence Homology, Nucleic Acid; Toxins; Vibrio parahaemolyticus; Vibrio parahaemolyticus - genetics; Vibrio parahaemolyticus - pathogenicity; Virulence - genetics; Vibrio parahaemolyticus; virulence plasmid; AHPND; shrimp; Pir toxin
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1503129112

Acute hepatopancreatic necrosis disease (AHPND) is a severe, newly emergent penaeid shrimp disease caused by Vibrio parahaemolyticus that has already led to tremendous losses in the cultured shrimp industry. Until now, its disease-causing mechanism has remained unclear. Here we show that an AHPND-causing strain of V. parahaemolyticus contains a 70-kbp plasmid (pVA1) with a postsegregational killing system, and that the ability to cause disease is abolished by the natural absence or experimental deletion of the plasmid-encoded homologs of the Photorhabdus insect-related (Pir) toxins PirA and PirB. We determined the crystal structure of the V. parahaemolyticus PirA and PirB (PirA(vp) and PirB(vp)) proteins and found that the overall structural topology of PirA(vp)/PirB(vp) is very similar to that of the Bacillus Cry insecticidal toxin-like proteins, despite the low sequence identity (<10%). This structural similarity suggests that the putative PirAB(vp) heterodimer might emulate the functional domains of the Cry protein, and in particular its pore-forming activity. The gene organization of pVA1 further suggested that pirAB(vp) may be lost or acquired by horizontal gene transfer via transposition or homologous recombination.