28 Questions
What type of bacteria have two membranes?
Klebsiella pneumoniae
What can protect the bacteria when they shed antibiotics and act as a 'decoy' when antigens are shed?
Outer membrane vesicles (OMV)
Which type of bacteria has a thick peptidoglycan wall?
Staphylococcus aureus
What can facilitate infection when they contain virulence factors, DNA, RNA, immunomodulatory factors, and adhesins?
Outer membrane vesicles (OMV)
What is a major global threat according to the text?
'Antibiotic resistance'
What must be understood to develop new therapeutic strategies?
Bacterial life cycle
What is difficult to get into bacteria that may kill them?
Antibiotics
What will immune cells try to kill and be busy with, according to the text?
Outer membrane vesicles (OMV)
What contains transporters and secretion machinery?
Both gram negative and gram positive bacteria
Which bacterial secretion system can transfer DNA and proteins?
Type IV secretion system
Which type of bacteria can inject proteins across the plasma membrane and/or phagosomal membrane?
Gram-negative bacteria
Which cells work to clear bacteria and develop immunity?
Both macrophages and dendritic cells
What is involved in presenting peptides from pathogens to T-cells?
MHC Class I and II
Which mechanism induces specific engulfment of bacterial cells during phagocytosis?
$Zipper$ and $Trigger$ mechanisms both
What drives engulfment during phagocytosis?
$PIP$ changes reinforcing actin remodeling machinery activation
What do Type II secretion systems secrete?
Toxins and small molecules
What is the function of Type III secretion system effector proteins?
Varying widely in function
In which type of bacteria are secretion systems less well understood?
Gram-positive bacteria
Which cells have slower degradation processes during bacterial clearance?
Dendritic cells
Which bacterial effectors alter retromer and Mannose-6 phosphate transport to prevent a compartment from becoming hydrolytic?
Salmonella effectors
What drives bacterial movement through the cytosol?
Actin comet tails
Which bacterial lifestyle involves replicating within their own specialized vacuolar compartment?
Salmonella and Legionella
What is the preferred form of cell death from the point of view of bacteria, very inflammatory and involves membrane rupture?
Apoptosis
Which proteins sense damaged membrane and target them for degradation through an autophagic mechanism?
Galectins
Which bacterial effectors act as an “R-SNARE” and recruit early endosomal SNAREs Syntaxins 8, 7 and 13?
Salmonella effectors
What initiates recruitment of actin polymerization machinery in bacterial cells?
Bacterial membrane proteins
What do glycans recruit to sense damaged membrane and target it for degradation through an autophagic mechanism?
Galectins
What form of death involves loss of ATP, membrane rupture, and is inflammatory?
Pyroptosis
Study Notes
Bacterial Secretion Systems and Host Cell Interactions
- Bacteria use secretion systems to obtain nutrients, communicate, and facilitate disease through the delivery of virulence factors.
- 11 secretion systems have been discovered to date, capable of transporting virulence factors to the cytosol or directly inserting into the cell wall.
- Gram-negative bacteria can inject proteins across the plasma membrane and/or phagosomal membrane, with the Sec and Tat transport machinery being the oldest and found in all kingdoms.
- Type II secretion system secretes toxins and small molecules, disabling host protein synthesis and leading to lethal infection.
- Type III secretion system secretes effector proteins and shares similarity to components with flagellar apparatus, with effectors varying widely in function.
- Type IV secretion system can transfer DNA and proteins, while Type V/VI translocate portions of themselves.
- Secretion systems in Gram-positive bacteria are not as well understood as in Gram-negative bacteria, with many proteins remaining within the cell wall and facilitating bacterial binding to the host surface.
- Professional phagocytic cells, such as macrophages, work to clear bacteria and develop immunity, with dendritic cells having slower degradation processes.
- MHC Class I and II are involved in presenting peptides from pathogens to T-cells, activating CD4+ and CD8+ T cells for antibody production and cytotoxicity, respectively.
- Bacterial infection by phagocytosis involves two processes: Zipper and Trigger mechanisms, inducing specific engulfment of bacterial cells.
- Signaling by bacteria induces phosphatidylinositol (PIP) changes that drive engulfment, with PIPs reinforcing the recruitment and activation of actin remodeling machinery.
- Secreted effector proteins can be modified by the host and interfere with cell function, often requiring activation by host machinery.
Test your knowledge about the bacterial secretion systems and their interactions with host cells. Learn about the mechanisms of protein secretion, bacterial infection by phagocytosis, and the role of professional phagocytic cells in immunity.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
