L15 - Bacterial protein secretion and assembly of surface structures Flashcards
What is the primary structural difference between Gram-positive and Gram-negative bacteria?
Gram-positive bacteria have a single membrane, while Gram-negative bacteria have both an inner and outer membrane.
What are the two major secretion pathways used by Gram-positive bacteria?
Sec and Tat pathways.
How does the Sec pathway function?
It transports unfolded proteins across the inner membrane using ATP hydrolysis.
How does the Tat pathway function?
It transports folded proteins using the proton motive force.
Which bacterial type (Gram-positive or Gram-negative) has more complex secretion systems?
Gram-negative bacteria
Which secretion systems are exclusive to Gram-negative bacteria?
Type I, II, III, IV, V, and VI secretion systems.
What is the role of the Sec and Tat pathways in Gram-negative bacteria?
They assist in protein transport before entering other secretion systems.
What type of proteins does the Sec pathway transport?
Unfolded proteins.
What type of energy does the Sec pathway require?
ATP hydrolysis.
What happens to the signal peptide in the Sec pathway?
It is cleaved after translocation.
What type of proteins does the Tat pathway transport?
Folded proteins.
What energy source does the Tat pathway use?
Proton motive force.
Which secretion system transports unfolded proteins and requires both a signal and translocator?
Type II secretion system.
Which secretion system is known as the ‘autotransporter’ system?
Type V secretion system.
What is the function of the Type III Secretion System (T3SS)?
It injects effector proteins directly into host cells like a syringe.
How does the T3SS contribute to bacterial pathogenicity?
It manipulates host cell functions to favor bacterial survival.
What is the role of the Type VI Secretion System (T6SS)?
It delivers proteins into neighboring bacterial cells for competition.
How does the T6SS resemble the T3SS?
Both act as direct delivery mechanisms but have different targets.
How do bacterial secretion systems aid infection?
They help bacteria evade host defenses and manipulate host cells.
What are effector proteins?
Secreted bacterial proteins that alter host cell function.
How can bacterial secretion systems be targeted therapeutically?
By designing drugs that block these pathways to reduce virulence.
Why is research on secretion systems important for medicine?
It aids in developing new treatments for bacterial infections.
What role do secretion systems play in antibiotic resistance?
They can help bacteria resist antibiotics by expelling drugs or modifying host responses.
Why are animal models important in secretion system research?
They help assess bacterial pathogenicity and treatment efficacy.
How can bacterial structures be used in drug delivery?
They can be engineered to transport therapeutic molecules into cells.
What is the main characteristic of the Type I secretion system?
It transports proteins in a single step from the cytoplasm to the extracellular space.
What energy source does the T1SS use?
ATP-binding cassette (ABC) transporters.
Which bacterial species commonly use the T1SS?
Escherichia coli, Bordetella pertussis, Pseudomonas aeruginosa.
What is the role of the T2SS?
It transports folded proteins from the periplasm to the extracellular space.
What bacterial processes rely on the T2SS?
Toxin and enzyme secretion.
Which bacteria use the T3SS?
Salmonella, Shigella, Yersinia, Pseudomonas, E. coli.
Why is the T3SS important for bacterial virulence?
It allows direct injection of toxins into host cells.
What is a key feature of the T4SS?
It transports both proteins and DNA.
Which secretion system is used in bacterial conjugation?
Type IV secretion system.
Which pathogen uses T4SS for virulence?
Helicobacter pylori.
What is the unique feature of the T5SS?
The protein transports itself across the outer membrane.
What are the three subtypes of the T5SS?
Autotransporters, two-partner systems, and trimeric autotransporters.
What is the primary function of the T6SS?
It delivers toxins to competing bacteria.
How is the T6SS structurally related to another system?
It resembles a bacteriophage tail.
Which secretion system contributes to antibiotic resistance?
Type I secretion system (e.g., efflux pumps).
What secretion system is most associated with intracellular pathogens?
Type III secretion system.
Which system is used for DNA transfer between bacteria?
Type IV secretion system.
What secretion system uses a needle-like structure?
Type III secretion system.
Which secretion system can secrete folded proteins?
Type II secretion system.
Which secretion system is associated with biofilm formation?
Type V secretion system.
What secretion system is used by Vibrio cholerae?
Type II secretion system.
What secretion system is involved in bacterial competition?
Type VI secretion system.
What system does Pseudomonas aeruginosa use to secrete elastase?
Type II secretion system.
What secretion system is the main virulence factor in Yersinia pestis?
Type III secretion system.
What are the main functions of bacterial secretion systems?
They transport proteins and toxins essential for bacterial survival, communication, and infection.
How do bacterial secretion systems contribute to pathogenesis?
They allow bacteria to inject toxins, manipulate host cells, and evade immune defenses.
Why is the Sec pathway important for Gram-positive and Gram-negative bacteria?
It provides a pathway for transporting unfolded proteins across membranes.
What role does ATP hydrolysis play in bacterial secretion?
ATP hydrolysis drives the transport of proteins through the Sec pathway.
How does the Tat pathway differ from the Sec pathway?
The Tat pathway transports folded proteins and uses the proton motive force instead of ATP.
Which secretion systems require the Sec or Tat pathways for initial protein transport?
The Sec and Tat pathways assist in transporting proteins before they enter Type I–VI secretion systems.
How does the Type II secretion system transport proteins?
It moves proteins from the periplasm to the extracellular space using a translocator.
What makes the Type V secretion system unique?
It allows proteins to transport themselves across the outer membrane.
What is the main function of the Type III secretion system?
It injects effector proteins directly into host cells like a molecular syringe.
How does the Type III secretion system enhance bacterial virulence?
It enables bacteria to manipulate host cell processes to promote infection.
What is the structural similarity between the Type III and Type VI secretion systems?
Both systems use a needle-like apparatus for direct protein delivery.
How does the Type VI secretion system benefit bacteria?
It delivers toxins into competing bacteria, giving an advantage in microbial competition.
Which secretion system is most important in bacterial competition?
The Type VI secretion system is the primary system for interbacterial competition.
What role do effector proteins play in bacterial infections?
They alter host cell function to enhance bacterial survival and infection.
How can bacterial secretion systems be targeted for therapeutic interventions?
Drugs can be developed to block secretion system function, reducing bacterial virulence.
Why is research on bacterial secretion systems important for drug development?
It enables the design of new antibiotics and therapies targeting bacterial infections.
How do secretion systems help bacteria evade the host immune system?
They secrete proteins that interfere with immune detection and response.
Which bacterial secretion system resembles a bacteriophage tail?
The Type VI secretion system shares structural similarities with bacteriophage tails.
What is the significance of secretion systems in bacterial-host interactions?
They help bacteria establish infections by interacting with host cells and modifying their responses.
How can bacterial secretion systems be engineered for drug delivery?
Bacteria can be engineered to transport therapeutic molecules into target cells.
