Using S. cerevisiae as a model system to investigate V. cholera vopX-host cell protein interactions and phenotypes

• Type of Material: Article
• Authors: Michelle Dziejman, University of Rochester; Christopher H. Seward, University of Illinois at Urbana-Champaign; Alexander Manzella, University of Rochester; Mohammad Alam, Emory University; J. Scott Butler, University of Rochester
• Language: English
• Date: 2015-10-14
• Publisher: MDPI
• Publication Version: Final Published Version
• Copyright Statement: © 2015 by the authors; licensee MDPI, Basel, Switzerland.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3390/toxins7104099
• Title of Journal or Parent Work: Toxins
• ISSN: 2072-6651
• Volume: 7
• Issue: 10
• Start Page: 4099
• End Page: 4110
• Grant/Funding Information: The work was supported by NIH/NIAID AI 073785 to MD and NIH/NIGMS GM 09973 to JSB.
• Keywords: cholera; VopX; S. cerevisiae CWI pathway; Type 3 Secretion System
• Research Categories: Biology, Genetics; Biology, Cell; Health Sciences, Pathology

Abstract

Most pathogenic, non-O1/non-O139 serogroup Vibrio cholerae strains cause diarrheal disease in the absence of cholera toxin. Instead, many use Type 3 Secretion System (T3SS) mediated mechanisms to disrupt host cell homeostasis. We identified a T3SS effector protein, VopX, which is translocated into mammalian cells during in vitro co-culture. In a S. cerevisiae model system, we found that expression of VopX resulted in a severe growth defect that was partially suppressed by a deletion of RLM1, encoding the terminal transcriptional regulator of the Cell Wall Integrity MAP kinase (CWI) regulated pathway. Growth of yeast cells in the presence of sorbitol also suppressed the defect, supporting a role for VopX in destabilizing the cell wall. Expression of VopX activated expression of β-galactosidase from an RLM1-reponsive element reporter fusion, but failed to do so in cells lacking MAP kinases upstream of Rlm1. The results suggest that VopX inhibits cell growth by stimulating the CWI pathway through Rlm1. Rlm1 is an ortholog of mammalian MEF2 transcription factors that are proposed to regulate cell differentiation, proliferation, and apoptosis. The collective findings suggest that VopX contributes to disease by activating MAP kinase cascades that elicit changes in cellular transcriptional programs.