Where are Capsules found
Outside outer membrane
What does the D-glutamic acid capsule cause?
Anthrax disease
What bacteria causes Anthrax disease?
Bacillus anthacis
Serotype
Distinguishable strain
What does the polysaccharide capsule allow?
Adherence to respiratory tissue
2 antigen types on surface of bacteria
O and K antigen
O antigen, how many varieties?
lipopolysaccharide - 9 varieties
K-antigen, how many serotypes?
capsular polysaccharide - 80 serotypes
Hypervirulent
Highly harmful
What happens when a cell lacks a capsule?
No pneumonia
What is the effect of a laboratory culture?
Loss of capsule
What does the virulence factor allow bacteria to achieve?
- Colonization (movement + attachment to host)
- evade/inhibit immune response
- enter/exit cell
- obtain nutrition from host
Advantages of Capsule
- surface attachment
- avoids immune response/detergents
-protection in natural environments (dehydration)
Homopolymer
Single repeating unit
Heteropolymer
More than 1 elementary unit repeated
H antigen
flagella
Protective mechanism of capsule
inability of immune system to recognize via inhibition of complement and alternative pathway
6 Steps of Wzx-Wzy pathway
- making individual sugars
- assembled onto lipid anchor on cytoplasmic side inserted to IM
- Flip to periplasmic space (Wzx)
- Polymerization (Close interaction of Wzx and Wzy)
- Translocation through periplasmic space
a. allow polar carbs to translocate
b. entry point near IM - Linkage + attachment to phospholipid
Polymerase
long chain polymerization
OPX
OM periplasmic export
PCP
Polysaccharide co-polymerase
3 PArts of lipopolysaccharide
- Lipid A
- Core polysaccharide
- O antigen
Unique features of Lipid A
- 4 fatty acid chains
- KDO-core oligosaccharide
Importance of LPS
- replaces most phospholipids in OM (protection from recognition)
- stabilizes OM structure
