Date of Award

Summer 2020


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Document Type


Degree Name

Master of Science (MS) in Biology




Approximately 50% of the human population is infected with Helicobacter pylori, which can lead to gastrointestinal diseases such as ulcers and gastric adenocarcinoma. Helicobacter pylori strains are genetically variable, and some contain a DNA region called the cytotoxin associated gene pathogenicity island (cagPAI) that encodes virulence factors. Gastrointestinal disease associated with H. pylori are more likely to occur in infections with cagPAI positive strains. Helicobacter pylori has few known transcriptional regulators, but still must regulate expression to survive a constantly changing environment. A mechanism to facilitate this regulation was revealed in a transcriptome analysis conducted by Sharma et al. (2010) that identified 60 previously unknown small RNAs (sRNA) and suggested their role in gene regulation may be significant. Small RNAs are short non-coding transcripts that bind to target mRNAs through complementary base-pairing and regulate gene expression. Several sRNAs were identified in the cagPAI, and, to date, only one has been characterized. To learn more about cagPAI sRNAs and the genes they regulate, I characterized transcriptional regulatory sequences of two cagPAI sRNAs, HPnc2620 and HPnc2665, and used a bioinformatic approach to predict their target mRNAs. The results indicate that HPnc2620 promoter is TGTCCA- 23 nucleotides (nt) -TAAAAT and is controlled with two terminators, a Rho-dependent terminator, and a Rho-independent terminator. HPnc2665 has the promoter consensus sequences GTCAAA- 26 nt -TTGCAA and a transcriptional Rho-independent terminator. Both sRNAs were highly conserved in H. pylori, but not in non-pylori Helicobacter and were predicted to regulate various virulence factors including chemotaxis and flagellar genes, vacuolating cytotoxin A, cagPAI genes, and urease gene ureB.