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