Transcriptional regulation of hilE gene involved in Salmonella Typhimurium invasion
Salmonella enterica serovar Typhimurium uses a type three secretion system (TTSS) encoded on Salmonella Pathogenicity Island 1 (SPI1) to invade intestinal epithelial cells and cause a variety of diseases ranging from mild gastroenteritis to life hyphen threatening systemic infections. The genes encoding this machinery are regulated by the protein HilA. At the same time, the hilA gene is regulated by three homologous proteins that are from the AraC family: HilC, RtsA, and the most potent hilA activator, HilD. Numerous regulators control HilD at the protein level, one being HilE. However, we do not understand how hilE is regulated. Nonetheless, we do know that loss of HilE increases expression of hilA under both SPI1+ inducing and SPI1- repressing conditions, in which the bacteria is submitted to low oxygen concentrations. The purpose of this work was to understand the transcriptional regulation of hilE in Salmonella. To understand this regulation, we monitored hilE expression in lacZ transcriptional fusion on the most optimal media: lactose MacConkey medium. We chose the medium that allowed optimal observation of hilE expression. We performed transposon mutagenesis and identified mutants with altered hilE expression which are the ones that are of different color or appearance than the parental strain. Determination of the site of insertion using PCR and sequencing the T-POP mutants allowed us to identify genes that regulate hilE expression.
School:
University of Puerto Rico at Humacao
Department:
Microbiology
Research Advisor:
James Slauch
Department of Research Advisor:
Medical Microbiology
Year of Publication:
2008