Regulation Of Virulence Factors Flashcards
What are promotor regions
Promoter regions are specific DNA sequences located upstream (towards the 5’ end) of a gene that are responsible for initiating the transcription process. They are important because they provide binding sites for RNA polymerase and transcription factors, which together regulate the rate at which a gene is transcribed into RNA.
What are promotor genes Pt2
Promotor regions are no coding regions of dna
Promotor region is recognised by rna polymerase
Translation start site
Why are -35 and -10 sites important
So that the dna can be recognised by rna polymerase
Rna core enzyme + sigma factor =
Rna polymerase holoenzyme
What does the sigma factor work with the rna core enzyme to do
To recognise promotor regions
Sigma binds to -10 -35 and the transcription start point
It makes sure that the rna polymerase is oriented the right way
This is how rna polymerase recognises promotor regions and transcription can start
What are transcriptional regulators
Repressors
Or
Activators
Transcriptional repressor
Sits in the way of RNA polymerase (sit between -10 and TSP(+1)
It will physically block RNA from passing
Transcriptional activators
Interacts with Rna polymerase and the dna
Helps rna polymerase to pass along dna and transcribe it
How do TFs know where to bind
Transcription factors bind to motifs within DNA called operators
Operators are often palindromic
A single transcription regulator/factor can regulate several genes
Transcription factors are proteins that bind to specific DNA sequences and either activate or repress gene expression. Some transcription factors have broad specificity and can bind to multiple genes, while others have more specific binding preferences and only target a subset of genes.
The ability of transcription factors to regulate multiple genes allows for complex gene expression programs to be coordinated in response to changes in the cellular environment or developmental cues.
What are operons and regulons
An operon is a unit of bacterial gene expression that consists of a cluster of genes that are transcribed together as a single mRNA molecule from a single promoter region. This allows for the coordinated regulation of multiple genes involved in a common biological pathway or function. The genes within an operon are typically related in function and are under the control of a common regulatory mechanism.
A regulon, on the other hand, is a group of genes that are controlled by a common regulatory protein or transcription factor, but are not necessarily clustered together on the chromosome like operons. The genes in a regulon can be located anywhere on the genome and may be involved in diverse biological functions. The regulatory protein or transcription factor that controls the regulon recognizes specific DNA sequences, such as promoter regions or enhancers, and can activate or repress the expression of the genes in the regulon.
What is an operator
In genetics, an operator is a specific DNA sequence located near the promoter region of an operon that is recognized by a regulatory protein
What is Diptheria toxin
Diphtheria toxin is a potent protein exotoxin produced by the bacterium Corynebacterium diphtheriae
- C.diphtheria is a gram + , aerobic, Rid bacteria
How does Diphtheria toxin work
The toxin works by inhibiting protein synthesis in host cells, causing cell death and tissue damage. It is composed of two subunits, A and B. The B subunit binds to specific receptors on the surface of host cells, while the A subunit enters the cell and disrupts protein synthesis.
What is the diphtheria vaccine
Inactivated toxin
What are two of the virulence factors of C.diphtheria
Production of siderophores
Production of A-B toxins that disrupts protein synthesis
When are toxins produced in C.diphtheria
Stationary phase
When nutrients became limiting
It is limiting iron that causes toxin release
What happens when C.diphtheria is in host with low iron
The host Is often an iron starved condition
Bacteria induced siderophores
Steals iron from transferrin and lactoferrin
Because siderophore production and toxin production are co regulated genes
What repressor is on C.diphtheria DNA
dtxR repressor
What does dtxR repressor do
It is responsive to low iron levels
So when bacteria is in fine iron levels it will remain on DNA ( on promotor region ) and the transcription of siderophores and tox genes won’t happen
If iron is deficient, repressor will release from DNA allowing the transcription of Siderophores and toxins which are co regulated
Ribosome binding site is also known as
Shine-Dalgarno sequence (SD sequence). It is a short nucleotide sequence found in the mRNA (messenger RNA) molecule, upstream of the start codon (usually AUG) that encodes the first amino acid of the protein. The RBS/SD sequence plays a crucial role in the initiation of translation, as it serves as the recognition site for the small ribosomal subunit to bind to the mRNA and begin the process of protein synthesis.
How can bacteria talk to each other
Quorum sensing
(Using chemical signals)
How does bacterial quorum sensing work
When there is low bacteria cell density you get low number of chemical signals produced
So you would observe bacteria individual behaviours
When there is a high bacteria cell density, you get a high number of chemical signals produced
So you would observe group bacteria behaviours
Example of group bacteria behaviour
Biofilm formation
- biofilms only form when the population gets to a certain density
What are the chemical signals produces by bacteria involved in quorum sensing called
AIs autoinducers
What can auto inducers be
Small molecules
Or
Peptides
What happens when Vibrio fischeri (gram-) hit a certain density
The bacteria become luminescent
(Symbiont of marine animals)
