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
Kimura, Satoshi; Hubbard, Troy P; Davis, Brigid M et al. (2016) The Nucleoid Binding Protein H-NS Biases Genome-Wide Transposon Insertion Landscapes. MBio 7:
Hatzios, Stavroula K; Abel, Sören; Martell, Julianne et al. (2016) Chemoproteomic profiling of host and pathogen enzymes active in cholera. Nat Chem Biol 12:268-74
Dörr, Tobias; Alvarez, Laura; Delgado, Fernanda et al. (2016) A cell wall damage response mediated by a sensor kinase/response regulator pair enables beta-lactam tolerance. Proc Natl Acad Sci U S A 113:404-9
Sasabe, Jumpei; Miyoshi, Yurika; Rakoff-Nahoum, Seth et al. (2016) Interplay between microbial d-amino acids and host d-amino acid oxidase modifies murine mucosal defence and gut microbiota. Nat Microbiol 1:16125
Chao, Michael C; Abel, Sören; Davis, Brigid M et al. (2016) The design and analysis of transposon insertion sequencing experiments. Nat Rev Microbiol 14:119-28
Hubbard, Troy P; Chao, Michael C; Abel, Sören et al. (2016) Genetic analysis of Vibrio parahaemolyticus intestinal colonization. Proc Natl Acad Sci U S A 113:6283-8
Dörr, Tobias; Delgado, Fernanda; Umans, Benjamin D et al. (2016) A Transposon Screen Identifies Genetic Determinants of Vibrio cholerae Resistance to High-Molecular-Weight Antibiotics. Antimicrob Agents Chemother 60:4757-63
Blondel, Carlos J; Park, Joseph S; Hubbard, Troy P et al. (2016) CRISPR/Cas9 Screens Reveal Requirements for Host Cell Sulfation and Fucosylation in Bacterial Type III Secretion System-Mediated Cytotoxicity. Cell Host Microbe 20:226-37
Yamaichi, Yoshiharu; Chao, Michael C; Sasabe, Jumpei et al. (2015) High-resolution genetic analysis of the requirements for horizontal transmission of the ESBL plasmid from Escherichia coli O104:H4. Nucleic Acids Res 43:348-60
Osorio, Carlos R; Rivas, Amable J; Balado, Miguel et al. (2015) A Transmissible Plasmid-Borne Pathogenicity Island Confers Piscibactin Biosynthesis in the Fish Pathogen Photobacterium damselae subsp. piscicida. Appl Environ Microbiol 81:5867-79

Showing the most recent 10 out of 87 publications