L15 - Bacterial protein secretion and assembly of surface structures

Question 1

What is the primary structural difference between Gram-positive and Gram-negative bacteria?

Answer 1

Gram-positive bacteria have a single membrane, while Gram-negative bacteria have both an inner and outer membrane.

Question 2

What are the two major secretion pathways used by Gram-positive bacteria?

Answer 2

Sec and Tat pathways.

Question 3

How does the Sec pathway function?

Answer 3

It transports unfolded proteins across the inner membrane using ATP hydrolysis.

Question 4

How does the Tat pathway function?

Answer 4

It transports folded proteins using the proton motive force.

Question 5

Which bacterial type (Gram-positive or Gram-negative) has more complex secretion systems?

Answer 5

Gram-negative bacteria

Question 6

Which secretion systems are exclusive to Gram-negative bacteria?

Answer 6

Type I, II, III, IV, V, and VI secretion systems.

Question 7

What is the role of the Sec and Tat pathways in Gram-negative bacteria?

Answer 7

They assist in protein transport before entering other secretion systems.

Question 8

What type of proteins does the Sec pathway transport?

Answer 8

Unfolded proteins.

Question 9

What type of energy does the Sec pathway require?

Answer 9

ATP hydrolysis.

Question 10

What happens to the signal peptide in the Sec pathway?

Answer 10

It is cleaved after translocation.

Question 11

What type of proteins does the Tat pathway transport?

Answer 11

Folded proteins.

Question 12

What energy source does the Tat pathway use?

Answer 12

Proton motive force.

Question 13

Which secretion system transports unfolded proteins and requires both a signal and translocator?

Answer 13

Type II secretion system.

Question 14

Which secretion system is known as the ‘autotransporter’ system?

Answer 14

Type V secretion system.

Question 15

What is the function of the Type III Secretion System (T3SS)?

Answer 15

It injects effector proteins directly into host cells like a syringe.

Question 16

How does the T3SS contribute to bacterial pathogenicity?

Answer 16

It manipulates host cell functions to favor bacterial survival.

Question 17

What is the role of the Type VI Secretion System (T6SS)?

Answer 17

It delivers proteins into neighboring bacterial cells for competition.

Question 18

How does the T6SS resemble the T3SS?

Answer 18

Both act as direct delivery mechanisms but have different targets.

Question 19

How do bacterial secretion systems aid infection?

Answer 19

They help bacteria evade host defenses and manipulate host cells.

Question 20

What are effector proteins?

Answer 20

Secreted bacterial proteins that alter host cell function.

Question 21

How can bacterial secretion systems be targeted therapeutically?

Answer 21

By designing drugs that block these pathways to reduce virulence.

Question 22

Why is research on secretion systems important for medicine?

Answer 22

It aids in developing new treatments for bacterial infections.

Question 23

What role do secretion systems play in antibiotic resistance?

Answer 23

They can help bacteria resist antibiotics by expelling drugs or modifying host responses.

Question 24

Why are animal models important in secretion system research?

Answer 24

They help assess bacterial pathogenicity and treatment efficacy.

Question 25

How can bacterial structures be used in drug delivery?

Answer 25

They can be engineered to transport therapeutic molecules into cells.

Question 26

What is the main characteristic of the Type I secretion system?

Answer 26

It transports proteins in a single step from the cytoplasm to the extracellular space.

Question 27

What energy source does the T1SS use?

Answer 27

ATP-binding cassette (ABC) transporters.

Question 28

What is the role of the T2SS?

Answer 28

It transports folded proteins from the periplasm to the extracellular space.

Question 29

What bacterial processes rely on the T2SS?

Answer 29

Toxin and enzyme secretion.

Question 30

Which bacteria use the T3SS?

Answer 30

Salmonella, Shigella, Yersinia, Pseudomonas, E. coli.

Question 31

Why is the T3SS important for bacterial virulence?

Answer 31

It allows direct injection of toxins into host cells.

Question 32

What is a key feature of the T4SS?

Answer 32

It transports both proteins and DNA.

Question 33

Which secretion system is used in bacterial conjugation?

Answer 33

Type IV secretion system.

Question 34

Which pathogen uses T4SS for virulence?

Answer 34

Helicobacter pylori.

Question 34

What is the unique feature of the T5SS?

Answer 34

The protein transports itself across the outer membrane.

Question 35

What are the three subtypes of the T5SS?

Answer 35

Autotransporters, two-partner systems, and trimeric autotransporters.

Question 36

What is the primary function of the T6SS?

Answer 36

It delivers toxins to competing bacteria.

Question 37

How is the T6SS structurally related to another system?

Answer 37

It resembles a bacteriophage tail.

Question 38

Which secretion system contributes to antibiotic resistance?

Answer 38

Type I secretion system (e.g., efflux pumps).

Question 39

What secretion system is most associated with intracellular pathogens?

Answer 39

Type III secretion system.

Question 40

What secretion system uses a needle-like structure?

Answer 40

Type III and VI secretion systems

Question 41

Which secretion system is associated with biofilm formation?

Answer 41

Type V secretion system.

Question 42

What secretion system is used by Vibrio cholerae?

Answer 42

Type II secretion system.

Question 43

What secretion system is involved in bacterial competition?

Answer 43

Type VI secretion system.

Question 44

What secretion system is the main virulence factor in Yersinia pestis?

Answer 44

Type III secretion system.

Question 45

What are the main functions of bacterial secretion systems?

Answer 45

They transport proteins and toxins essential for bacterial survival, communication, and infection.

Question 46

How do bacterial secretion systems contribute to pathogenesis?

Answer 46

They allow bacteria to inject toxins, manipulate host cells, and evade immune defenses.

Question 47

Why is the Sec pathway important for Gram-positive and Gram-negative bacteria?

Answer 47

It provides a pathway for transporting unfolded proteins across membranes.

Question 48

What role does ATP hydrolysis play in bacterial secretion?

Answer 48

ATP hydrolysis drives the transport of proteins through the Sec pathway.

Question 49

How does the Tat pathway differ from the Sec pathway?

Answer 49

The Tat pathway transports folded proteins and uses the proton motive force instead of ATP.

Question 50

Which secretion systems require the Sec or Tat pathways for initial protein transport?

Answer 50

The Sec and Tat pathways assist in transporting proteins before they enter Type I–VI secretion systems.

Question 51

How does the Type II secretion system transport proteins?

Answer 51

It moves proteins from the periplasm to the extracellular space using a translocator.

Question 52

What makes the Type V secretion system unique?

Answer 52

It allows proteins to transport themselves across the outer membrane.

Question 53

What is the main function of the Type III secretion system?

Answer 53

It injects effector proteins directly into host cells like a molecular syringe.

Question 54

How does the Type III secretion system enhance bacterial virulence?

Answer 54

It enables bacteria to manipulate host cell processes to promote infection.

Question 55

How does the Type VI secretion system benefit bacteria?

Answer 55

It delivers toxins into competing bacteria, giving an advantage in microbial competition.

Question 56

Which secretion system is most important in bacterial competition?

Answer 56

The Type VI secretion system is the primary system for interbacterial competition.

Question 57

What role do effector proteins play in bacterial infections?

Answer 57

They alter host cell function to enhance bacterial survival and infection.

Question 58

How can bacterial secretion systems be targeted for therapeutic interventions?

Answer 58

Drugs can be developed to block secretion system function, reducing bacterial virulence.

Question 59

Why is research on bacterial secretion systems important for drug development?

Answer 59

It enables the design of new antibiotics and therapies targeting bacterial infections.

Question 60

How do secretion systems help bacteria evade the host immune system?

Answer 60

They secrete proteins that interfere with immune detection and response.

Question 61

Which bacterial secretion system resembles a bacteriophage tail?

Answer 61

The Type VI secretion system shares structural similarities with bacteriophage tails.

Question 62

What is the significance of secretion systems in bacterial-host interactions?

Answer 62

They help bacteria establish infections by interacting with host cells and modifying their responses.

Question 63

How can bacterial secretion systems be engineered for drug delivery?

Answer 63

Bacteria can be engineered to transport therapeutic molecules into target cells.

Question 64

Which bacterial secretion systems are considered one-step systems in Gram-negative bacteria?

Answer 64

Type III, Type IV, and Type VI secretion systems directly span from the inner to the outer membrane without a periplasmic intermediate.

Question 65

What is a defining feature of Type V secretion systems (autotransporters)?

Answer 65

The protein contains all information necessary for its own transport across the outer membrane.

Question 66

What are the components of the Sec translocon complex?

Answer 66

SecA (ATPase), SecB (chaperone), and the SecYEG channel in the membrane.

Question 67

What triggers activation of the Type III secretion system?

Answer 67

Contact with a host cell triggers the T3SS to inject effector proteins into the host cytoplasm.

Question 68

What is the function of the translocon in Type III secretion systems?

Answer 68

It forms a pore in the host membrane to allow injection of bacterial effector proteins.

Question 69

What is a Tps system in Type Vb secretion?

Answer 69

Two-partner secretion, where one protein (TpsB) forms the pore and the other (TpsA) is the effector protein transported.

Question 70

What is the role of TatA in the Tat secretion pathway?

Answer 70

TatA oligomerizes to form the translocation pore for folded protein export.

Question 71

What kind of cellular processes can T3SS effectors manipulate in host cells?

Answer 71

They can alter actin cytoskeleton, modulate signaling, and facilitate bacterial uptake or adherence.

Question 72

Which proteins are often anchored to the Gram-positive cell wall via sortase enzymes?

Answer 72

Adhesins, invasins, and immune evasion proteins are often anchored via sortase enzymes.

Question 73

What type of secretion system is used by Gram-positive bacteria to export sortase substrates?

Answer 73

The Sec pathway is used to translocate sortase substrates across the membrane.

Question 74

How is the function of the Type VII secretion system linked to virulence?

Answer 74

It enables bacterial survival and host manipulation during infection.

Question 75

What structural feature allows Mycobacterium tuberculosis to require a specialised secretion system?

Answer 75

Its thick, lipid-rich envelope creates a need for specialised protein transport systems.

Question 76

Why do Gram-positive bacteria not require outer membrane secretion systems?

Answer 76

Because they lack an outer membrane, their secretion ends at the peptidoglycan or extracellular environment.

Question 77

What is the consequence of sortase A deletion in pathogenic Gram-positive bacteria?

Answer 77

Loss of sortase A impairs virulence due to lack of surface protein anchoring.

Question 78

What is needed for proteins to be Tat exported?

Answer 78

Folded and contain a N-terminal signal sequence with a twin arginine (RR) motif

Question 79

Explain TatB, TatC, and TatA

Answer 79

Fold pre protein recognises by tatb and tatc complex then delivered to TatA. TatA forms a channel

Question 80

What is needed for auto transporters?

Answer 80

N terminal passenger terminal and c terminal m translocator (beta barrel)