Enterohemorrhagic E. coli (EHEC) serotype O157:H7 is responsible for outbreaks of bloody diarrhea and hemolytic uremic syndrome throughout the world. The main reservoir for EHEC is cattle herds. EHEC colonization of cattle has been shown to require a functional locus of enterocyte effacement (LEE) region, involved in intestinal adhesion, and formation of lesions on enterocytes named attaching and effacing (AE) lesions, as well as a functional SdiA transcription factor. SdiA is a quorum sensing transcription factor that requires its autoinducer, an acyl-homoserine lactone (AHL) for proper folding and function. EHEC harbors SdiA, but does not produce an AHL autoinducer, consequently having to sense AHLs produced by other species of bacteria in the environment. These observations, combined with reports showing that AHLs are prominent within cattle rumen, suggest an important role for SdiA- AHL mediated regulation of EHEC genes necessary for colonization of the bovine gastrointestinal (GI) tract. We demonstrated that both synthetic AHLs, as well as AHLs extracted from cattle rumen repress expression of the LEE genes. However, the role of diet in modulating AHL levels within the rumen, and their correlation with EHEC shedding remain poorly understood. Furthermore, the mechanisms by which SdiA regulates transcription are still unknown. Finally, the distribution of an sdiA mutant within the intestinal tract of cattle, as well as a definitive reason underlying its attenuation remains to be established. Accordingly the Specific Aims of this study are:
Specific Aim 1 : To assess the presence of AHLs in rumen samples from cattle, as well as their correlation with diet and EHEC shedding.
Specific Aim 2 : Determine the molecular mechanisms of SdiA-dependent gene regulation.
Specific Aim 3 : Characterize the distribution of an sdiA mutant within the bovine intestine, and better define the basis for this mutant's diminished ability to colonize cattle.

Public Health Relevance

Enterohemorrhagic E.coli (EHEC) serotype O157:H7 is the agent responsible for outbreaks of bloody diarrhea throughout the world. The main reservoir for EHEC is cattle herds. Consequently, diminishing cattle colonization and shedding of EHEC is of great interest to human health. In this grant proposal, we aim to understand how a signaling mechanism between bacterial cells through a small molecule called acyl-homoserine lactone, which is present in the rumen of cattle, controls expression of EHEC genes necessary for virulence and colonization of the bovine intestine.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI077613-04
Application #
8212172
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Baqar, Shahida
Project Start
2009-02-13
Project End
2014-01-31
Budget Start
2012-02-01
Budget End
2013-01-31
Support Year
4
Fiscal Year
2012
Total Cost
$378,024
Indirect Cost
$111,731
Name
University of Texas Sw Medical Center Dallas
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
800771545
City
Dallas
State
TX
Country
United States
Zip Code
75390
Gruber, Charley C; Sperandio, Vanessa (2014) Posttranscriptional control of microbe-induced rearrangement of host cell actin. MBio 5:e01025-13
Curtis, Meredith M; Hu, Zeping; Klimko, Claire et al. (2014) The gut commensal Bacteroides thetaiotaomicron exacerbates enteric infection through modification of the metabolic landscape. Cell Host Microbe 16:759-69
Hernandez-Doria, Juan D; Sperandio, Vanessa (2013) Nutrient and chemical sensing by intestinal pathogens. Microbes Infect 15:759-64
Sheng, Haiqing; Nguyen, Y N; Hovde, Carolyn J et al. (2013) SdiA aids enterohemorrhagic Escherichia coli carriage by cattle fed a forage or grain diet. Infect Immun 81:3472-8
Njoroge, Jacqueline W; Gruber, Charley; Sperandio, Vanessa (2013) The interacting Cra and KdpE regulators are involved in the expression of multiple virulence factors in enterohemorrhagic Escherichia coli. J Bacteriol 195:2499-508
Nguyen, Y N; Sheng, Haiqing; Dakarapu, Rambabu et al. (2013) The acyl-homoserine lactone synthase YenI from Yersinia enterocolitica modulates virulence gene expression in enterohemorrhagic Escherichia coli O157:H7. Infect Immun 81:4192-9
Hughes, David T; Terekhova, Darya A; Liou, Linda et al. (2010) Chemical sensing in mammalian host-bacterial commensal associations. Proc Natl Acad Sci U S A 107:9831-6