Bacteriology test 2

3 steps of general secretory pathway

1. Protein guided by chaperones to site

2. Protein chain crosses the lipid bilayer

3. Signal protein cleaved off chain

Why is the general secretory pathway important?

Secretes specific proteins bacteria need to colonize host. 

Type 1 secretion system

Located in gram negative only because it goes across inner and outer membrane. Activated by the concentration of calcium. Made of 3 proteins and is specific for certain proteins.  Also Sec-independent

Why is type 1 secretion system important?

Directly secretes proteins outside cytoplasm!

Type 3 secretion system

Inside gram negatives only!

Contact dependent!

Only works between live eukaryotic cells

Needle like structure protrudes out bacterial cell to penetrate eukaryotic and inject proteins into the cytoplasm.

Proteins from bacterial cytoplasm → Eukaryotic cytoplasm

Secretion is dependent on calcium concentration

Use translocated effectors to modify cytoskeleton and invade the tissues of the eukaryote.

Ways to use type 3 secretion system

Maybe use bacteria to inject cancer killing proteins into eukaryotic cancer cells. Only allow bacteria to interact with tumor cells and inject them with something to suppress and eliminate growth.

Type 4 secretion system

Impact on bacterial pathogenesis

Sec independent

Uses large amount of proteins

Only in gram negatives

Transfers monomeric, multimeric and single stranded DNA across membranes

Can transfer DNA from one bacteria to another or eukaryotic cell

Three different types: conjugation, DNA uptake, and effector translocation. 

Uses of Type 4 secretion system

Use bacteria to deliver DNA to other cells. Can edit genes. Can transfer antibiotic resistance to other bacteria (not good), deliver plasmids expressing desired proteins.

Tuberculosis

Has unusual glycolipids in cell wall

Can develop TB through infected aerosols but they will stay in lungs and stay asymptomatic.

Lives in part of lung with low oxygen

Develops more when immunosuppressed and bacteria will start to attack and bind the macrophages in the lungs and move to cavitary TB.

Macrophages unable to break down TB due to unusual glycolipids in cell wall

Diagnosis of TB is hard because test won’t be positive until after week 4

Treatment for TB is synthesis of mycolic acid activated by a catalyst.

Chlamydia

Gram negative

most common STD

most easily preventable form of blindness

usually asymptomatic

More common in females than males

In females can lead to inflammatory pelvic disease

has elemental and reticulate bodies for the developmental cycle

CPAF enzyme destroys host immune proteins

Pseudomonas

Soil bacterium found all over world

gram negative

More common to get pseudomonas if you have burn wounds

Use oxidase test to test for pseudomonas

a big issue is that it forms biofilms on biomaterials

can contaminate mouthwash

produces fungicidal components

Bacterial communication signals

can use chemicals

pyrone based signaling allows for recognition of each other to form biofilm

Synthesis recognize respond

Signals are recognized by LuxR- type receptors

can be apart of bad for bacteria because makes cells more susceptible to killing by eukaryotes innate immune system

Bacterial biofilms

Mostly gram positive cocci

the bacteria are held together by a polysaccharide matrix

A problem is that biofilms can form on plastic implants (like catheters) and infect individual

Microbiome

All organisms composing in or on an individual

How does lyme disease transfer from tick to human?

Tick attaches to host and drinks blood

Blood travels to stomach where bacteria travels to salivary glands to then infect next individual that tick bites. 

Borrelia burgdorfelia

causes lyme disease

compacted segmented genome

periplasmic flagellum

limited metabolic capacities

has many transporters because relies on host for nutrients

no production of amino acids, fatty acids or nucleotides