Lecture 2 Flashcards by Carter Duggan

What mechanism do bacteria use for uptake?

Rocker-switch mechanism

No endocytosis

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What system do bacteria use to transport sugars?

Phosphotransferase system (PTS)
If glucose is low, somethign stays phosphorylated, cAMP is produced, alternate carbon sources are used

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What are energy sources for rocker-switch mechanism?

Membrane potential
Gradient of another solute
ATP hydrolysis

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Type I SecMech

3 linked proteins form pore through IM, peri, OM
ATP powers secretion
E. coli hemolysin
Pseudomonas proteases
Pasturella leukotoxin

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Type II SecMech

Sec B recognizes leader peptide
Sec A is ATPase
SecYEG is translocon
Periplasmic leader protease 
Specific or semi-specific OM porin
MOST SECRETED PROTEINS IN BACTERIA AND MITOCHONDRIA USE THIS MECHANISM

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Type III SecMech

Virulence secretory pathway
One step mechanism
Shigella (Ipas)
Salmonella (Sips)
Yersinia (Yops)

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Type IV SecMech

Transport DNA and proteins
Two paradigm systems
1. Agrobacterium tumifaciens VirB/TraF
2. Dot/Icm sytstem in many pathogens
a. Legionella pneumophila
b. Helicobacter pylori
c. Bordetella pertussis

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Type V SecMech

Autosecretion
Sec B leader on N term through IM
Beta domain on C term spontaneously forms channel through OM
Brucella, E. Coli and others

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Type VI SecMech

Genes usually located in pathogenicity islands
Structurally similar to bacteriophage tail fiber
Very common

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What forms peptidoglycan backbone

N-acetylglucosamine
N-acetylmuramic acid
Linked beta 1-4

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Which type of bacteria has pentapeptide cross bridge of peptidoglycan?

GramPos

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What is the pentapeptide side chain added to?

UDP N-acetylmuramic acid

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What is the MurNAc with pentapeptide added to?

Bactoprenol

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What happens after MurNAc PP is added bactoprenol?

Flips to other side of membrane when BP is phosphorylated. It is then added into a hole in the membrane. Finally crosslinking occurs. BP is dephosphorylated and it flips back in

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What blocks UDP addition to MurNAc?

Fosfomycin

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What inhibits flipping of bactoprenol?

Bacitracin

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What CLASS blocks transpeptidases?

Beta-lactams

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What blocks transglycosidase?

Glycopeptides

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What are the special wall components of GramPos?

Teichoic acid (Mg+ reserve, phosphate)
Teichuronic acid
Lipoteichoic acid

What is one function of lipoteichoic acid?

Links PG to membrane

What are holes in the OM?

Porins (three proteins)
Non-Allow MW less than 600
semi, specific

What links OM to PG layer?

Lipoprotein (Brauns protein)

Linked to DAP in PG

What is another name for LPS?

Endotoxin

What binds LPS?

LBP after the bacteria has been lysed
LBP then binds to CD14 and TLR4
Induces secretion of lymphokines

What are major effects of lymphokines?

Increase synthesis of WBC | Increase capillary permeability

What is the repeating unit in LPS

O-antigen

Why is LOS more virulent than LPS?

Resemble mammalian sphingolipids and evade host defense

How is LPS synthesized?

1. Core is added as monosaccharide to lipid A on cyto side 2. Flips to peri side 3. Repeat unit is synthesized on cyto side, added to bactoprenol and flips 4. Finished LPS translocates to OM by bridging proteins

What is mycolic acid used for?

Waxy protective coating

What is function of arabinogalactan and arabinomannan

Anchors waxy part of wall to to PG | Activates HIV-1 expression

What is the purpose of the capsule or glycocalyx?

Adhesions to surface Anti-phagocytic Immune mimic

What are pili and fimbriae

Short hollow cylinders of pilin and fimbrin

What are functions of pili and fimbriae?

Hold cells together Attach cells to surface Antigenic (cells can vary this to evade hosts) Motility (twitching)

What are flagella composed of?

Flagellin

How does a flagella move?

Protons move through Mot A/B which causes a repulsion

What are the three stages of germination?

I-activation. Permeabilizes coat II-initiation-binding of germinant releases autolysin and DPA is released III-outgrowth-until first division of new cell

CCW rotation of flagella causes what?

Swimming

CW rotation of flagella causes what?

Cell tumbles randomly

What is S-layer?

A layer that surrounds some cells Acts as a sieve Might have anti-complement properties

When do endospores form?

Only under starvation conditions | This triggers membrane kinases that start a phosphorylation cascade ending with SpooA-P

What is a spore?

A metabolically inactive bacteria with a double membrane around its genetic material

What event reactivates a spore?

Germination

What can trigger germination of a spore?

Binding of nutrients

What is the difference in peptidoglycan residues between GramNeg and Pos?

``` Neg = DAP at #3 Pos = Lysine at #3 ```

What are all capsules?

Polysaccharides except for B. anthracis