title: Transcriptome sequencing reveals the virulence and environmental genetic programs of Vibrio vulnificus exposed to host and estuarine conditions.
abstract: Vibrio vulnificus is a natural inhabitant of estuarine waters worldwide and is of medical relevance due to its ability to cause grievous wound infections and/or fatal septicemia. Genetic polymorphisms within the virulence-correlated gene (vcg) serve as a primary feature to distinguish clinical (C-) genotypes from environmental (E-) genotypes. C-genotypes demonstrate superior survival in human serum relative to E-genotypes, and genome comparisons have allowed for the identification of several putative virulence factors that could potentially aid C-genotypes in disease progression. We used RNA sequencing to analyze the transcriptome of C-genotypes exposed to human serum relative to seawater, which revealed two divergent genetic programs under these two conditions. In human serum, cells displayed a distinct "virulence profile" in which a number of putative virulence factors were upregulated, including genes involved in intracellular signaling, substrate binding and transport, toxin and exoenzyme production, and the heat shock response. Conversely, the "environmental profile" exhibited by cells in seawater revealed upregulation of transcription factors such as rpoS, rpoN, and iscR, as well as genes involved in intracellular signaling, chemotaxis, adherence, and biofilm formation. This dichotomous genetic switch appears to be largely governed by cyclic-di-GMP signaling, and remarkably resembles the dual life-style of V. cholerae as it transitions from host to environment. Furthermore, we found a "general stress response" module, known as the stressosome, to be upregulated in seawater. This signaling system has been well characterized in Gram-positive bacteria, however its role in V. vulnificus is not clear. We examined temporal gene expression patterns of the stressosome and found it to be upregulated in natural estuarine waters indicating that this system plays a role in sensing and responding to the environment. This study advances our understanding of gene regulation in V. vulnificus, and brings to the forefront a number of previously overlooked genetic networks.
authors.affiliation: Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America.
authors.forename: Tiffany C
authors.initials: TC
authors.lastname: Williams
authors.affiliation: Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America.
authors.forename: Elliot R
authors.initials: ER
authors.lastname: Blackman
authors.affiliation: Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America.
authors.forename: Shatavia S
authors.initials: SS
authors.lastname: Morrison
authors.affiliation: Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America.
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Gibas
authors.affiliation: Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America.
authors.forename: James D
authors.initials: JD
authors.lastname: Oliver
mesh_terms: D001422:Bacterial Adhesion / Q000235:genetics; D018441:Biofilms / Q000254:growth & development; D002633:Chemotaxis / Q000235:genetics; D004777:Environment; D063366:Estuaries; D020869:Gene Expression Profiling; D005838:Genotype; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D012623:Seawater / Q000382:microbiology; D017423:Sequence Analysis, RNA; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D041261:Vibrio vulnificus / Q000166:cytology / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
chemical_list: D014157:Transcription Factors