Identification and characterization of Vibrio vulnificus plpA encoding a phospholipase A2 essential for pathogenesis

Kyung Ku Jang, Zee Won Lee, Bityeoul Kim, Young Hyun Jung, Ho Jae Han, Myung Hee Kim, Byoung Sik Kim, Sang Ho Choi

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The marine bacterium Vibrio vulnificus causes food-borne diseases, which may lead to life-threatening septicemia in some individuals. Therefore, identifying virulence factors in V. vulnificus is of high priority. We performed a transcriptome analysis on V. vulnificus after infection of human intestinal HT29-methotrexate cells and found induction of plpA, encoding a putative phospholipase, VvPlpA. Bioinformatics, biochemical, and genetic analyses demonstrated that VvPlpA is a phospholipase A2 secreted in a type II secretion system-dependent manner. Compared with the wild type, the plpA mutant exhibited reduced mortality, systemic infection, and inflammation in mice as well as low cytotoxicity toward the human epithelial INT-407 cells. Moreover, plpA mutation attenuated the release of actin and cytosolic cyclophilin A from INT-407 cells, indicating that VvPlpA is a virulence factor essential for causing lysis and necrotic death of the epithelial cells. plpA transcription was growth phase– dependent, reaching maximum levels during the early stationary phase. Also, transcription factor HlyU and cAMP receptor protein (CRP) mediate additive activation and host-dependent induction of plpA. Molecular biological analyses revealed that plpA expression is controlled via the promoter, PplpA, and that HlyU and CRP directly bind to PplpA upstream sequences. Taken together, this study demonstrated that VvPlpA is a type II secretion system-dependent secretory phospholipase A2 regulated by HlyU and CRP and is essential for the pathogenicity of V. vulnificus.

Original languageEnglish
Pages (from-to)17129-17143
Number of pages15
JournalJournal of Biological Chemistry
Volume292
Issue number41
DOIs
StatePublished - 13 Oct 2017

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