Mobile genetic elements have profoundly influenced the evolution of bacterial pathogens. Many determinants of virulence and antibiotic resistance are borne by mobile elements, such as plasmids and bacteriophages, which are capable of horizontal transmission. During this grant cycle, we studied several aspects of the life cycle of CTXF, a filamentous phage that encodes cholera toxin, the principal virulence factor of the cholera pathogen Vibrio cholerae. We described novel mechanisms that mediate the integration of CTXF into the V. cholerae chromosome and that govern CTXF gene expression. We also expanded the scope of our work to explore several aspects of the molecular biology of SXT, a V. cholerae-derived integrating conjugative element (ICE) that encodes multiple antibiotic resistance genes. In recent years, SXT and closely related elements have become highly prevalent in V. cholerae clinical isolates. Our long-term goal is to decipher the molecular mechanisms that enable the dissemination of CTXF and SXT. We propose to explore 5 aspects of the molecular biology of CTXF and SXT that govern their transmission and evolution. Experiments in Aim I to elucidate mechanisms that control expression of RstR, the CTXF repressor, will reveal how two host factors, LexA and RpoS, contribute to the novel genetic circuitry governing CTXF production.
In Aims II -V, we will explore the molecular bases for aspects of the SXT life-cycle that distinguish this mobile element from phages and plasmids. Studying these novel features of SXT will enhance our understanding of ICEs, an extensive and medically important set of mobile elements that have not been subject to intensive study, and will shed light on processes that have contributed to the prevalence and diversity of SXT-related ICEs in the gamma proteobacteria. In particular, we will explore II) steps in SXT conjugation that limit its transfer to new hosts, III) genes required for SXT maintenance in donor cells, IV) mechanisms for preventing redundant transmission of SXT to hosts in which it is already present and V) processes by which new/hybrid SXT-related ICEs are generated. Completion of these studies will enhance our understanding of the mechanisms that control of horizontal gene transfer and yield knowledge of fundamental aspects of prokaryote cell biology and pathogen evolution. Furthermore, these studies may provide valuable information for the creation of new antimicrobial agents and vaccines.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37AI042347-17
Application #
8204963
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Hall, Robert H
Project Start
1998-01-01
Project End
2012-12-31
Budget Start
2012-01-01
Budget End
2012-12-31
Support Year
17
Fiscal Year
2012
Total Cost
$343,035
Indirect Cost
$147,015
Name
Brigham and Women's Hospital
Department
Type
DUNS #
030811269
City
Boston
State
MA
Country
United States
Zip Code
02115
Livny, Jonathan; Zhou, Xiaohui; Mandlik, Anjali et al. (2014) Comparative RNA-Seq based dissection of the regulatory networks and environmental stimuli underlying Vibrio parahaemolyticus gene expression during infection. Nucleic Acids Res 42:12212-23
Möll, Andrea; Dörr, Tobias; Alvarez, Laura et al. (2014) Cell separation in Vibrio cholerae is mediated by a single amidase whose action is modulated by two nonredundant activators. J Bacteriol 196:3937-48
Pritchard, Justin R; Chao, Michael C; Abel, Sören et al. (2014) ARTIST: high-resolution genome-wide assessment of fitness using transposon-insertion sequencing. PLoS Genet 10:e1004782
Okada, Ryu; Zhou, Xiaohui; Hiyoshi, Hirotaka et al. (2014) The Vibrio parahaemolyticus effector VopC mediates Cdc42-dependent invasion of cultured cells but is not required for pathogenicity in an animal model of infection. Cell Microbiol 16:938-47
Kota, Swathi; Charaka, Vijaya K; Ringgaard, Simon et al. (2014) PprA contributes to Deinococcus radiodurans resistance to nalidixic acid, genome maintenance after DNA damage and interacts with deinococcal topoisomerases. PLoS One 9:e85288
Espaillat, Akbar; Carrasco-López, César; Bernardo-García, Noelia et al. (2014) Structural basis for the broad specificity of a new family of amino-acid racemases. Acta Crystallogr D Biol Crystallogr 70:79-90
Taylor, Dawn L; Bina, X Renee; Slamti, Leyla et al. (2014) Reciprocal regulation of resistance-nodulation-division efflux systems and the Cpx two-component system in Vibrio cholerae. Infect Immun 82:2980-91
Dörr, Tobias; Möll, Andrea; Chao, Michael C et al. (2014) Differential requirement for PBP1a and PBP1b in in vivo and in vitro fitness of Vibrio cholerae. Infect Immun 82:2115-24
Munera, Diana; Ritchie, Jennifer M; Hatzios, Stavroula K et al. (2014) Autotransporters but not pAA are critical for rabbit colonization by Shiga toxin-producing Escherichia coli O104:H4. Nat Commun 5:3080
Millet, Yves A; Alvarez, David; Ringgaard, Simon et al. (2014) Insights into Vibrio cholerae intestinal colonization from monitoring fluorescently labeled bacteria. PLoS Pathog 10:e1004405

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