Lecture 12: Bacterial Exotoxins Flashcards
True or False: Exotoxins are nucleic acids
False - proteins
True or False: Exotoxins are found in gram negative and positive bacteria and can be detected at human/animal/insect cells
True
True or False: Exotoxins can be made into effective vaccines and treat conditions like CP
True
True or False: Exotoxin is important for survival and propagation of bacterium that produce them
True
Where are the toxin genes commonly carried on?
1.
2.
1) Plasmids and 2) Lysogenic bacteriophages - e.g Diptheria
True or False: Some exotoxins are not excreted. Rather, they accumulate inside cell and are released by cell lysis.
True
____: a specific term that denotes exotoxins released by bacteria in intestines, which can cause diarrhea or vomiting
Enterotoxin
___ is embedded in bacterial surface and released when bacteria lysis
LPS (endotoxin)
What are the three types of toxins?
- Type 1 (Superantigen toxins/surface acting)
- Type II (Membrane-Disrupting Toxins)
- Type III Toxins (A-B Toxins)
Type ___ Toxins bind to host cell surface but is not translocated into host cell. Further, it allows for binding to MHC Class II and receptor on T cells that interact with MHC.
Type I
Many ___ cells can be stimulated by bridging action of superantigens
A. B cells
B. T cells
C. Macrophages
B. T cells
What symptoms arise as a result of Type I toxins?
Nausea, vomit, malaise, fever (toxic shock syndrome)
Three examples of type 1 toxins?
- TSST (S. aureus)
- Streptococcal
- Enterotoxin (E. coli)
Which toxin lysis the host cell by disrupting integrity of their cytoplasmic membranes?
A. Type 1
B. Type 2
C. Type 3
B. Type 2
What are the two different types of Type 2 (Membrane Disrupting) Toxins?
- Pore forming cytotoxins
- Enzyme cytotoxins
The primary role of Type II toxins is to kill host cells, particularly ____
phagocytes
S. aureus alpha-hemolysin is an example of which bacterial exotoxin?
A. Type 1
B. Type 2
C. Type 3
B. Type 2 - pore
Invasive bacteria use Type __ exotoxins to escape from phagosome and enter host cell cytoplasm
A. Type 1
B. Type 2
C. Type 3
B. Type 2
_____ cytotoxins insert into host cell membrane and make open channel (pore), which triggers a sudden inrush of water. This causes cell to swell and rupture.
A. Enzyme cytotoxin
B. Pore-forming cytotoxin
B. Pore-forming cytotoxin
Which Type II toxin destabilizes host cell membranes by either 1) removing charged head group of lipid portion or 2) cleave at other sites on the phospholipid
A. Enzyme cytotoxin
B. Pore-forming cytotoxin
A. Enzyme cytotoxin
Phospholipase, hemolysin, and cytotoxin are examples of which type of Type II toxin?
A. Pore-forming exotoxin
B. Enzyme cytotoxins
B. Enzyme cytotoxins
True or False: Type III (A-B Toxins) Toxins are extracellular acting
False - intracellular
In Type III Exotoxins, the A subunit is the active, ___ light chain while the B subunit is the heavy chain and is responsible for __
enzymatic; binding
True or False: In both simple and complex Type III Exotoxins, the B portion binds to a specific host cell receptor, then translocation regions moves A portion into host cell cytoplasm (either via : endocytosis or directly)
True
The compound AB toxin has a B portion made up of __ subunits and __ A subunit
A. one; multiple
B. multiple; one
B. multiple; one
When does the A subunit of AB Toxin become enzymatically active and exert its toxic effects?
Once A Portion is in the cytoplasm
True or False: The A portion of A-B Toxins may enter very different cell types and will likely catalyze DIFFERENT reactions
False - the A portion of A-B Toxins may enter very different cell types, but most of them catalyze the SAME reaction (removal of the ADP-ribosyl group from NAD and attach it to host cell protein)
In Type III exotoxins, the ____ of the host cell protein either inactivates it or causes it to behave abnormally
ADP-ribosylation
Diptheria, Cholera, and Shiga are examples of which exotoxin?
A. Type I
B. Type II
C. Type III
C. Type III
The A portion of ADP-ribosylates elongation factor 2 in which of the following:
A. Diptheria
B. Cholera
C. Shiga
A. Diptheria
What is the effect of the A portion of diptheria toxin?
To kill host cell by stopping protein synthesis
____: The A portion of AB Toxin will add ADP-ribosylate to a regulatory enzyme that controls cAMP levels in host cell. It keeps enzyme from being turned OFF, causing host cell to lose control of ION FLOW. Diarrhea results.
A. Diptheria
B. Cholera
C. Shiga
B. Cholera
The A subunit of the AB toxin cleaves a host cell rRNA molecule, which results in shutdown of protein synthesis in which pathogen?
A. Diptheria
B. Cholera
C. Shiga
C. Shiga
What kind of antibodies are the body’s major defense against exotoxins?
Antitoxin antibodies
True or False: Once the antibody binds to the exotoxin (B subunit) the toxin can no longer bind to receptors on host cell membrane
True
Which toxin enters the blood stream, but some bacteria still remain in throat (toxemia)?
A. Cholera
B. Diptheria
C. Shiga
B. Diptheria
Which toxin is made by clostridium and is a gram (+) obligate anaerobe, as well as a sporeformer?
A. C. diff
B. E. coli
C. Botulinum
C. Botulinum toxin
True or False: Food borne botulism is an infection
False - food borne botulism is NOT an infection. Rather: it’s an intoxication…
In botulism, target neurons attack ____ endings. Inside the neuron, the toxin blocks release of ____, a neurotransmitter.
peripheral; Ach
Which two types of botulism involve COLONIZATION of the bacteria, followed by toxin production?
Wound botulism and infant botulism
What three toxins are produced by clostridium botulinum toxin?
- Botox (botulinum)
- C2 toxin
- C3 toxin
True or False: C2 and C3 toxin catalyze ADP-ribosylation of host cell proteins while C1 (botox) act on neurons
True
True or False: Tetanus toxin, produced by clostridium tetani, can cause lockjaw
True
True or False: Clostridium botulinism causes patient to develop spastic paralysis - primary effect of CNS
False - Clostridium Tetani does this
Which toxin blocks release of inhibitors from inhibitor interneurons?
A. Botox toxin
B. Tetanus toxin
B. Tetanus toxin
Both ___ and ___ are neurotoxins
Botulism and Tetanus
Both Botulism and Tetanus share AA sequence similarity with zinc-requiring endopeptidase, which cleaves a set of proteins known as _____
synaptobrevins
____ are found in synaptic vesicles of neurons, the vesicles responsible for release of NT and inhibitory mediators
Synaptobrevins
Why do Botulism and Tetanus cause such different effects?
Cell specificities of the binding regions of the two toxins
Botulinum toxin targets ___ neurons while tetanus toxin acts on ______
peripheral; CNS
Which toxin cleaves SNARE’s, thereby preventing neuro-secretory vesicles from docking/fusing with the nerve synapse plasma membrane and releasing their neurotransmitters?
A. Diptheria
B. Clostridium
C. Botulin
Botulin toxin
___ toxin, produced by clostridium perfringens, contribute to gangrene by killing host cells and utilizing phospholipase activity
A. Alpha toxin
B. Beta toxin
C. Gamma-toxin
Alpha-toxin
Alpha toxin is a:
A. Type 1 Toxin
B. Type 2 Toxin
C. Type 3 Toxin
B. Type 2 Toxin (membrane disrupting)
True or False: Alpha-toxin targets many cell types and hydrolyzes lipid lecithin in mammalian cell membranes
True
Which pathogen contributes to toxic shock syndrome?
Toxic shock syndrome pathogen
True or False: Staphylococcus aureus produces most TSST (toxic shock syndrome toxins)
True
TSST is a
A. Type 1 toxin
B. Type 2 toxin
C. Type 3 toxin
A. Type 1 toxin
- supertoxin
What is the target cell for TSST (Toxic shock syndrome toxin-1)?
A. T Cells
B. B cells
C. Both B and T Cells
D. Macrophages
T cells
True or False: TSST causes non-specific binding of T cells macrophages, elicits cytokine production by T cells, and produces fever
True
Which toxin produces Pasturellosis? Is it gram (+) or gram (-)?
Pasteurella multocida toxin (PMT) - gram negative
True or False: Pasteurella multocida toxin causes bone/weight loss, as well as lung destruction
True
Which toxin binds the gangliosides receptor and enters cell via receptor mediated endocytosis?
A. TSST
B. Diptheria
C. Clostridium dificil
D. Pasteurella multocida toxin
Pasteurella multocida toxin
True or False: Pasteurella multocida toxin turns the G protein OFF, which permanently disrupts regulation of cellular activities
False - Pasteurella multocida toxin turns the G protein ON, which permanently disrupts regulation of cellular activities
True or False: Pasteurella multocida toxin is a type III toxin
True
