Regulation of Virulence Factors

Question 1

What is the sigma factor?

Answer 1

A sigma factor is a protein needed for initiation of transcription in bacteria. It is a bacterial transcription initiation factor that enables specific bindign of RNA polymerase to gene promoters

Question 2

What is negative control of transcription regulation?

Answer 2

Regulatory protein shuts down trasncription

Question 3

What is positive control of transcription regulation?

Answer 3

Regulatory protein triggers transcription

Question 4

Whats special about transcription regulators?

Answer 4

A single regulator can regulate several genes

Question 5

What kind of factor regulates the expression of virulence factors and give examples?

Answer 5

Environmental cues signal the entry into the host tissues and indues expression of virulence facotors:
Low iron
Tempreture
pH
Oxygen tension
Stress

Question 6

Why was the vaccination against Diptheria successful?

Answer 6

2 vaccinations given
One against Siderophore production
One agaisnt the Tox production (A-B type toxin)

Question 7

How does Diphtheria release toxins in iron limiting conditions?

Answer 7

At stationary phase, nutrients become limiting
Tox protein encoded by tox gene produces the Diphtheria toxin causingan intake of iron—-> damage to tissue—->loss of iron—-> could mean a decrease in RBC
tox gene expression increases in iron starved cultures

Question 8

What is the action of the Diphtheria toxin repressor to low iron levels?

Answer 8

Iron replete—> stops toxin and siderophore production
Iron deficient—> Repressor stops—-> toxin and siderophore production increase.

Question 9

What is quorum sensing in bacterial populations?

Answer 9

Quorum sensing is a process of cell–cell communication that allows bacteria to share information about cell density and adjust gene expression accordingly

Question 10

What is one example of quorum sensing?

Answer 10

LuxI/R system- symbiont to marine animals–>bioluminescent
Baby bobtail squid do not have light organs when they hatch, butas they develop, the squid secrete a mucus gel to which V. fischeri binds. Then, ciliated cells within the ducts leading to the light organs help the bacteria to migrate up to the light organs, where they colonize
and grow. Once the density of the bacteria reaches a certain threshold, the bacteria turn on the Lux system, which produces bioluminescence, and the light organs begin to glow