Award Date
May 2023
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Life Sciences
First Committee Member
Helen Wing
Second Committee Member
Boo Shan Tseng
Third Committee Member
Eduardo Robleto
Fourth Committee Member
Ernesto Abel-Santos
Number of Pages
122
Abstract
Nucleoid-structuring proteins (NSPs) in bacterial cells can exert gene regulatory effects over great distances on DNA. This contrasts with the traditional view of bacterial transcriptional regulation, where transcription factors bind cis-acting regulatory sites proximal (<250 bp) to promoters to influence gene expression. In Shigella species, the histone-like nucleoid-structuring protein (H-NS) transcriptionally silences many genes on the large (~220 kb) virulence plasmid. During host colonization, however, silencing by H-NS is alleviated by the anti-silencer protein, VirB, which remodels the H-NS:DNA complex. This transcriptional anti-silencing is mediated by VirB:DNA interactions and the modulation of DNA supercoiling, which lead to the up-regulation of virulence genes. VirB is a central regulator of Shigella virulence, but the mechanistic basis for transcriptional regulation is incompletely characterized. Here, I focus on the potential for VirB to regulate transcription from remotely located DNA binding sites. Employing complementary in vivo approaches, I assessed the spatial stringency of the VirB binding site and elucidated how varying cellular VirB levels impacts regulation over different distances. I also evaluated how a molecular roadblock on DNA influences remote regulation by VirB. Additionally, I developed control tools to validate the ability of VirB to spread along DNA, an activity of VirB that putatively drives transcriptional regulation. These data are consistent with transcriptional anti-silencing being driven by VirB spreading along DNA. Overall, these findings highlight how VirB is not a conventional transcriptional regulator and broaden our perspective on transcriptional control in bacteria. Furthermore, this work contributes to our understanding of long-range gene regulatory effects, which are frequently overlooked and poorly characterized in bacteria.
Keywords
Chromosome remodeling; Histone-like nucleoid-structuring protein; Remote regulation; Transcriptional anti-silencing; Transcriptional regulator; Transcriptional silencing
Disciplines
Biology | Microbiology | Molecular Biology
Degree Grantor
University of Nevada, Las Vegas
Language
English
Repository Citation
Cris, Cody, "Long-Range Regulation by the Shigella Virulence Gene Regulator, VirB" (2023). UNLV Theses, Dissertations, Professional Papers, and Capstones. 4665.
https://digitalscholarship.unlv.edu/thesesdissertations/4665
Rights
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