Lecture 8 - Innate Immunity and Bacteria Flashcards
Pathogens detected by TLR 1/2 and 2/6
Bacteria, mycobacteria, fungi
Which bacteria have LPS?
Gram -
Which part of a bacterial cell wall gives resistance to many proteolytic enzymes?
D-isoform of amino acids
Where is peptidoglycan in G- bacteria?
Periplasmic space
Structure of peptidoglycan
1) N-acetylmuramic acid
2) N-acetylglucosamine
3) N-acetylmuramic acids linked by 4 amino acid oligopeptide chains
What are the oligopeptides in peptidoglycan made up of?
D- and L- amino acids
What does lysozyme degrade?
Polysaccharide bond between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycan
Typical G+ genera
Streptococcus, staphylococcus, bacillus
Thickness of peptidoglycan in G+ bacteria
20 - 80nm
Acidic polysaccharides in G+ peptidoglycan
1)
2)
1) Teichoic acid - Polymer of ribitol or glycerol and phosphate
2) Lipoteichoic acid - teichoic acid linked to lipids in cell wall
Typical Gram- genera
Salmonella, Escherichia
Typical width of periplasmic space
20 - 70nm
Composition of G- outer membrane 1) 2) 3) 4)
1) Protein (EG: porins)
2) Lipoprotein
3) Phospholipid
4) Lipopolysaccharide
Proportion of G- outer membrane that is lipid
15%
Part of LPS that is toxic
Lipid A
Most conserved part of LPS
Lipid A
Most variable part of LPS
O-specific polysaccharide
Major parts of LPS
1)
2)
3)
1) Lipid A
2) Core polysaccharide
3) O-specific polysaccharide
What determines whether LPS is smooth or rough?
Smooth - long chain O-specific polysaccharide
Rough - short chain O-specific polysaccharide
Result of excess lipid A in the blood
Raised temperature
Fever - septic shock, endotoxic shock
Molecule used to serogroup bacteria
O-specific polysaccharide
TLR activated by cell wall components
TLR1, 2, 4, 6
Examples of bacteria that stain Gram negative, but are Gram positive
Mycobacterium, Nocardia
Bacterium that lacks a cell wall
Mycoplasma
Composition of glycocalyx in bacteria
Usually polysaccharide
Can be polypeptide, or both
Capsule glycocalyx structure
ORganised, repeating units attached to cell surface
Slime layer glycocalyx structure
Loose, water-soluble structure
Function of capsules and slime layers 1) 2) 3) 4) 5)
1) Prevent dessication
2) Prevent phagocytosis
3) Prevent opsonisation
4) Promote biofilm formation
5) Promote adhesion
Which type of pathogenic bacteria often have glycocalyces?
Blood-borne pathogens
How is a bioflim on the teeth formed?
1)
2)
1) Bacteria attach to salivary proteins on tooth surface
2) Provides anaerobic environment for bacteria to flourish
Parts of a prokaryotic flagellum
1)
2)
3)
1) Filament
2) Hook
3) Basal body
Type of bacteria with sialic acid-rich capsule
Neisseria meningitidis type B
Prokaryotic movement patterns
1)
2)
1) Runs - Straight lines
2) Tumbles - Rapid, abrupt changes in direction
What is H type?
Type of flagellum that a bacteria has
Organisation of E. coli flagella
Multiple lateral flagella
Organisation of Vibrio flagella
Single polar flagellum
Organisation of T. pallidum flagella
Periplasmic flagella
Flagella are located in periplasmic space, ‘vibrate’ bacteria
How conserved are flagella?
Very
TLR5 detects many types of flagella
Subunit making up filament of flagella
Flagellin
Structure of pili
1) Rod-shaped, hollow cylinder
2) Helical array of pilin protein subunits
3) Pilus tip mediates adhesion - can be pilin or another protein
What is tissue tropism?
Tip of pilus determines tissue specific adhesion
