Flashcards in Regulation of Salmonella Virulence Deck (21):
Why is S. typhimurium useful to study in mice even though it is not the cause of typhoid fever in humans?
In mice, it mimics the effects that S. typhi has in humans and essentially produces the same result.
How does acid tolerance in salmonella contribute to virulence?
Acid tolerance allows for the survival in the stomach, which allows the bacteria to reach the intestines where they can enact their pathogenicity.
How is acid tolerance generated in salmonella?
The acid shock proteins
Is salmonella intracellular or extracellular?
What is SP1?
Many of the genes required for invasion are located on a 40-kB pathogenicity island called SPI1 (SALMONELLA PATHOGENICITY ISLAND).
What are some genes that are encoded from SP1?
inv and spa
What do inv and spa code for?
Type III secretory protein that is used to export Sip proteins into cells
How does M cell entry occur?
Type III secretory protein is used to export Sip proteins into the M cell that cause ruffling of the M cell and leads to phagocytosis of the salmonella
Within the phagosome, how does the salmonella survive?
It inhibits fusion of the phagosome with the lysosome
How does the salmonella enter macrophages after entering a phagosome in the M cell?
The lack of phagosome-lysosome fusion allows the bacterial cell to transit through the M cell to interact with a macrophage where it uses a second Type III secretory system to facilitate macrophage phagocytosis
What does prgHIJK encode?
The Type III secretory protein used for entry into macrophages
What are the parts of the Two Component Signal Transduction?
Sensor - His Autokinase
Response Regulator - Asp DNA Binding Protein
How does the 2CST system function?
Membrane bound His sensor will have ATP donate Pi on activation which will lead to Pi of the Asp response regulator leading to DNA binding to either activate or repress genes.
What is the PhoQP system of salmonella?
It is a 2CST system used for invasion and survival in the macrophage to signal when the cell has reached the inside of a macrophage
What is PhoQ?
PhoQ is a membrane-bound histidine kinase sensor that senses low Mg2+ concentrations
What is PhoP
PhoP is its cognate response regulator that functions as a DNA-binding protein. Phospho-PhoP represses genes required for invasion into M cells and macrophages
What are prg genes?
prg - genes for invasion of M cells
What are pag genes?
pag - genes for survival in the macrophage
What happens to the regulation of prg and pag when PhoQ senses that salmonella has reached the inside of a macrophage?
Phospho-PhoP represses genes required for invasion into M cells and macrophages (prg). Simultaneously, it activates genes required for survival in macrophage (pag).
Is PhoQP required for virulence?
Because null mutants of PhoP are attenuated.