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dc.contributor.advisorVázquez-Torres, Andrés A.
dc.contributor.advisorChurchill, Mair E.
dc.contributor.authorTapscott, Timothy Gregory
dc.date.accessioned2017-01-06T22:35:02Z
dc.date.available2017-06-16T08:20:26Z
dc.date.submitted2016
dc.identifierTapscott_ucdenveramc_1639D_10383.pdf
dc.identifier.urihttp://hdl.handle.net/10968/1759
dc.descriptionIncludes bibliographical references.
dc.descriptionFall
dc.description.abstractMicrobial pathogens like Salmonella utilize numerous strategies to rapidly sense and respond to a myriad of environmental stresses. Oxidative, nitrosative, and nutritional stress imposed by the innate immune response are prominent among the antimicrobial pressures encountered by Salmonella during their association with mammalian hosts. The stringent response to nutritional stress, which is under the control of the RNA polymerase-binding protein DksA and the nucleotide alarmone guanosine penta/tetraphosphate [(p)ppGpp], is essential for Gram-negative pathogens to respond to nutrient limiting conditions. This stress program activates transcription of amino acid biosynthetic genes while repressing the expression of translational machinery. Investigations presented in this thesis indicate that, in addition to controlling the stringent response to nutritional stress, DksA and (p)ppGpp promote the transcription and translation of genes encoding the Salmonella Pathogenicity Island 2 (SPI2) virulence program. Control of SPI2 expression affords Salmonella the ability to minimize contact with lysosomes and vesicles containing NADPH oxidase or inducible nitric-oxide synthase while overcoming the nutrient limitations found in vesicles of the degradative pathway. My research suggests that DksA contributes to Salmonella pathogenesis largely through regulation of SPI2. Positive feedback of SPI2 expression by DksA and (p)ppGpp may balance virulence gene expression with metabolic limitations imposed by the innate immune response. DksA is under post-translational regulation by reactive oxygen and nitrogen species that modify conserved thiols in the globular domain of this RNA polymerase regulatory protein, thus promoting resistance to oxidative and nitrosative stress. Investigations presented herein have elucidated regulatory outputs of the thiol-based sensor DksA, and have demonstrated that oxidized DksA inhibits transcription of amino acid biosynthesis genes livJ and hisG, the ribosomal gene rpsM, and the SPI2 effector gene sifA. These investigations indicate that oxidized DksA regulates gene transcription independently of the stringent response. Furthermore, my research has identified Asp71 at the tip of the coiled-coil domain of DksA to be an essential residue for transducing the regulatory output in response to oxidative and nitrosative stress. Salmonella expressing dksA D71N were found to be hypersusceptible to reactive oxygen and nitrogen species and were attenuated in a murine model of salmonellosis. Together, these investigations have revealed multifaceted roles by which the thiol-based sensor DksA contributes to Salmonella pathogenesis.
dc.format.extent151 pages
dc.languageEnglish
dc.language.isoeng
dc.publisherUniversity of Colorado at Denver, Anschutz Medical Campus. Health Sciences Library
dc.rightsCopyright of the original work is retained by the author.
dc.subjectstringent response
dc.subjectDksA
dc.subjectSPI2
dc.subject.meshSalmonella
dc.subject.meshOxidative Stress
dc.titleContribution of thiol-based sensor dksA to Salmonella pathogenesis
dc.typeThesis
dc.identifier.schemaETD Data Dictionary 1.1
dc.rights.accessEmbargo Expires: 06/19/2017
dcterms.embargo.terms2017-06-19
dcterms.embargo.expires2017-06-19
dc.contributor.committeememberColgan, Sean P.
dc.contributor.committeememberVoskuil, Martin I.
dc.contributor.committeememberSchurr, Michael J.
dc.contributor.committeememberBarton, David J.
thesis.degree.nameDoctor of Philosophy (Ph.D.)
thesis.degree.levelDoctoral
thesis.degree.disciplineMolecular Biology
thesis.degree.grantorUniversity of Colorado at Denver, Anschutz Medical Campus


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