Year: 2017
Type: dissertation
Abstract: Shigella species, including Shigella dysenteriae, are causative agents of bacillary \ndysentery, a disease characterized by severe diarrhea and blood in the stool. Although a number \nof genes required for virulence have been characterized in S. dysenteriae, others remain to be \nidentified. These additional virulence-associated genes can be identified by screening mutants of \nS. dysenteriae in a plaque assay. The plaque assay is used to infer virulence by measuring the \nability of the bacteria to invade, grow within, and spread between eukaryotic cells, resulting in \nthe formation of plaques, small holes in a monolayer of eukaryotic cells. Mutants that have lost \nthe ability to form normal plaques are necessarily avirulent. \nA previously described non-directed mutant, SDU380, lost the ability to form plaques. \nFurther characterization revealed that this strain had sustained a 33 kilobase deletion. None of \nthe genes in the deleted region are known virulence genes. The purpose of this study was to \nidentify and characterize a novel virulence gene in this deleted region that resulted in the \ninability of SDU380 to form plaques. Different mutant strains missing only some of the genes \ndeleted in SDU380 were constructed and tested for virulence in a plaque assay. This analysis \nrevealed that the loss of the gene yciB is responsible for the failure of SDU380 to form plaques. \nThe role of the protein YciB in S. dysenteriae virulence is unknown, though the yciB gene is a \nknown virulence-associated gene in Shigella flexneri, a species with a similar lifestyle to that of \nS. dysenteriae. In S. flexneri, YciB plays a role in septation, an essential step in cell division. \nFurther analysis showed that loss of YciB in S. dysenteriae also results in an intracellular growth \ndefect. However, this defect does not seem to be due to loss of ability to undergo septation and \nno growth defect is observed in vitro.
DOI: 10.15781/t2vm43c92
Author: Hilgendorf, Keren
Language: English
Subfield: Endocrinology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W1822857741