The host factor (HF-I) proteins of Escherichia coil and Salmonella RNA binding proteins that are required for optimal translation of the mRNA encoding the stationary phase specific alternative c factor RpoS. The hfq gene encodes HF-I, and E. coil and S. typhimurium hfq mutants display essentially the same generalized stationary phase defective phenotype as E. coil and S. typhimurium rpoS mutants. Previous studies in our laboratory have shown that the B. abortus hfq mutant Hfq3 displays a generalized stationary phase defect in vitro, but more importantly, mutational studies have clearly established that HF-I is required for the wild-type virulence of B. abortus 2308 in the mouse model. In studies funded by our current award from NIAID, we have identified 18 genetic loci in B. abortus 2308 that are regulated by HF-I, 6 of which are required for wild-type virulence in mice. Three (ahpCD, sodC and cydAB) encode stationary phase antioxidants that protect the intracellular brucellae from oxidative damage in the phagosomal compartment. Interestingly, the virB operon (which encodes the Type IV secretion system) and the bvrRS two-component regulatory system (which regulates genes involved in maintaining cell envelope integrity) also require HF-I for normal expression in B. abortus 2308. The Brucella spp. lack a typical RpoS homolog, so the nature of the regulatory link between HF-I and stationary phase gene expression in not yet clear. Consequently, the objectives of the project described in this competing renewal application are a) to investigate the individual contributions of the B. abortus HF-I regulated genes dps, cfa, znuA, oppD, and bolA to stationary phase physiology in vitro and virulence in mice; b) to better define the role of HF-I in the regulation of the virB and bvrRS operons, and c) to test the hypothesis that the alternative a factor RpoE2 links HF-I and stationary phase gene expression in B. abortus 2308, and thus serves as a """"""""functional RpoS homolog in this bacterium. Defining the basis for HF-I mediated stationary phase gene expression in Brucella and elucidating the contributions of individual stationary phase gene products to successful survival and replication in host macrophages will provide us with important basic information that will be useful for the design of novel vaccine candidates and improved chemotherapeutic approaches.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI048499-06A2
Application #
7038666
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Mukhopadhyay, Suman
Project Start
2000-07-15
Project End
2011-04-30
Budget Start
2006-05-01
Budget End
2007-04-30
Support Year
6
Fiscal Year
2006
Total Cost
$325,109
Indirect Cost
Name
East Carolina University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
607579018
City
Greenville
State
NC
Country
United States
Zip Code
27858
Budnick, James A; Sheehan, Lauren M; Colquhoun, Jennifer M et al. (2018) Endoribonuclease YbeY Is Linked to Proper Cellular Morphology and Virulence in Brucella abortus. J Bacteriol 200:
Saadeh, Bashir; Caswell, Clayton C; Chao, Yanjie et al. (2016) Transcriptome-Wide Identification of Hfq-Associated RNAs in Brucella suis by Deep Sequencing. J Bacteriol 198:427-35
Sheehan, Lauren M; Budnick, James A; Roop 2nd, R Martin et al. (2015) Coordinated zinc homeostasis is essential for the wild-type virulence of Brucella abortus. J Bacteriol 197:1582-91
Caswell, Clayton C; Elhassanny, Ahmed E M; Planchin, Emilie E et al. (2013) Diverse genetic regulon of the virulence-associated transcriptional regulator MucR in Brucella abortus 2308. Infect Immun 81:1040-51
Kim, Hye-Sook; Caswell, Clayton C; Foreman, Robert et al. (2013) The Brucella abortus general stress response system regulates chronic mammalian infection and is controlled by phosphorylation and proteolysis. J Biol Chem 288:13906-16
Caswell, Clayton C; Baumgartner, John E; Martin, Daniel W et al. (2012) Characterization of the organic hydroperoxide resistance system of Brucella abortus 2308. J Bacteriol 194:5065-72
Caswell, Clayton C; Gaines, Jennifer M; Ciborowski, Pawel et al. (2012) Identification of two small regulatory RNAs linked to virulence in Brucella abortus 2308. Mol Microbiol 85:345-60
Martin, Daniel W; Baumgartner, John E; Gee, Jason M et al. (2012) SodA is a major metabolic antioxidant in Brucella abortus 2308 that plays a significant, but limited, role in the virulence of this strain in the mouse model. Microbiology 158:1767-74
Caswell, Clayton C; Gaines, Jennifer M; Roop 2nd, R Martin (2012) The RNA chaperone Hfq independently coordinates expression of the VirB type IV secretion system and the LuxR-type regulator BabR in Brucella abortus 2308. J Bacteriol 194:3-14
Steele, Kendra H; Baumgartner, John E; Valderas, Michelle Wright et al. (2010) Comparative study of the roles of AhpC and KatE as respiratory antioxidants in Brucella abortus 2308. J Bacteriol 192:4912-22

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