Biol 4215 Exam 3 LSU

OspA

outer surface protein in lyme bacteria. Present inside tick when temperature is low (25 C) It helps the bacteria adhere to the stomach of the tick. Decreases when temperature of tick increases

OspC

Outer surface protein of lyme bacteria. Is only present when the temperature is that of mammals (37 C). So when the tick bites the animal, OspC production increases. This allows the bacteria to move from the stomach to the salivary glands of the tick.

VlsE

A surface lipoprotein that has antigenic variation which allows the surface of the bacteria to change during the process of infection.

Antigenic variation

VlsE has silent cassette genes in front of it that it uses to incorporate into its surface protein to provide a plethora of different antigens in order to avoid detection by the immune system

Gram Negative Quorum Sensing

LasI produce Acylhomoserine lactone (Quorum sensing molecule) which is permeable to cell membranes, then activates LasR which binds to DNA.

Gram positive quorum sensing

Use small peptides as their quorum sensing signal. Peptides are not cell permeable and interact with a cell surface receptor/sensor kinase in order to enter the cell.

Type III effector proteins

1) ExoU

2) ExoS

3) ExoT

4) ExoY

ExoT

Prevents phagocytosis by

1) Targeting Rho and inactivates it thro hydrolysis of GTP (GAP activity)

2) Targeting Crk and ADP-ribosylating it. (inhibits Crks protein-protein interaction)

ExoS

prevents phagocytosis by

1) Targeting Rho and inactivating it thro GAP activity

2) *Targets ERM and ADP ribosylation blocks its normal phosphorylation capability

Similiarities between ExoT and ExoS

They both have Rho GAP activity, and ADP-ribosylation activity. They both have 2 targets and 2 mechanisms that inhibit phagocytosis.

ExoU

Used to break host cells membranes. Phospholipase A2: enzyme that targets phospholipids breaks esterbond at the 2 position of phospholipids and releases a arachidonic fatty acid , which feeds into eicosanoid synthesis (inflammation).

Exotoxin A

enters host cell and targets EF2 and ADP-ribosylates an amino acid on it, to render it non functioning and stop protein synthesis.

Type IV pili

Allow bacteria to adhere to host cell

Type II secretion

Secrete pili and toxins. The synthesis/elongation of pili in the periplasm/middle membrane pushes the toxin out of the cell.

L. monocytogenes properties

Gram positive rod shaped bacteria that uses host actin for mobility and can withstand a large range of temps. It escapes into the cytoplasm of host cells and spreads to adjacent cells.

Internalin A ( InlA )

Cell surface protein that binds to E-cadherin host receptor, which is in tight junctions. This cell surface protein helps with endocytosis of bacteria.

Internalin B (InlB)

Cell surface protein that binds to host Met receptor, and uses Clathrin mediated endocytosis to be engulfed.

Listerolicen O (LLO)

Pore forming Toxin that allows the bacteria to escape the endosome and enter the cytoplasm. It is activated by a cholesterol membrane and low pH.

Phospholipase C (PLC)

contributes to the breakdown of the endosome

ActA

Recruits ARP2/3 and increases its activity which is to recruit Monomeric Actin to it and uses them to make polymerized actin. This is done to propel the bacteria forward.

Efferocytosis and Listeria monocytogenes

Listeria uses the hosts efferocytosis ability to promote cell to cell transfer. They damage the cell cytoskeleton which produces Phosphatidylserine on the cell surface which is recognized by macrophages Tim4 receptors to engulf the injured cell. Listeria then infects that macrophage in the same way

Zoonose

Disease that can be transmitted from animals to humans

What kind of bacterial shape is Borrelia burgdorferi?

Spirochetes

Borrelia burgdorferi's genome is mainly (circular/linear)

Linear. This is unique to Borrelia

Lipoproteins

Proteins that are secreted into the periplasm via the SEC pathway. In the periplasm, they are modified with a lipid and can be docked into the cytoplasmic or outer membrane

What is unique about Borrelia's lipoproteins?

Mainly surface-exposed.

What is an important signal for the changing expression of Borrelia's lipoproteins?

Temperature:

OspC is synthesized at 37C

OspC is not synthesized at 24C

Which of the following temperatures is OspC synthesized? 37C or 24C

37C- within the mammal

Variable major protein (VlsE)

Has the potential for antigenic variation by recombination of normally silent alleles allowing for distinct forms of VlsE protein to be expressed

Phase variation

Simplest form of antigenic variation

Doesn't involve genetic mutation

Simply turning a gene on, or turning a gene off

How to calculate phenotypes of phase variation

# of phenotypes= 2^N

Where N is number of independently regulated genes

Serotype

Bacteria that are antigenically similar

Mosaic effect

Borrelia burgdorfi can express many distinct antigens at one time

Where are the combined (variable) regions present in the Borrelia glycolipid

The "cone" top

Antibodies are most likely directed to this site

OspA is present when the Borrelia is in (tick/mammal)

Tick

OspC is present when the Borrelia is in (tick/mammal)

Mammal

VlsE is present when the Borrelia is in (tick/mammal)

Mammal

Of the following, which is most necessary for Borrelia infection and why: OspA, OspC or VlsE

OspC

Pseudomonas aeruginosa

Gram negative

Found in soil

Resistant to most antibiotics

Lots of virulence factors (LPS, TIIISS, Exotoxin A, Biofilm formation)

Steps of biofilm formation

Attachment

Growth

Dispersal

Acyl-homoserine lactones

Used by gram negative bacteria for quorum sensng

Genes required for growth of biofilm:

LasR response regulator

LasI

LasI

Required for synthesis of a mature biofilm

Makes acylhomoserine lactone.

Takes an acyl chain from an acyl carrier protein and uses S-adenosyl-methionine

T/F: All bacteria have a form of LasI

True

DeltaLasI Borrealis mutant characteristic:

Able to adhere to surfaces but unable to form the architecture of a mature biofilm

Alginate

Coating that surrounds pseudomonas when it is in the CF lungs to mask it from host immune system.

arr

Aminoglycoside resistance regulator

Is a phosphodiesterase that cleaves a small molecule called cyclic-di-GMP

In the pond environment, there is (high/low) c-di-GMP.

In the human environment, there is (high/low) c-di-GMP

High=biofilms

Low

c-di-GMP effector functions

Motility

Virulence

Sessility and biofilm formation

Cell cycle progression

Pseudomonas' Type III secretion system secretes:

ExoU

ExoT

ExoS

ExoY

Which Pseudomonas effector molecule disrupts tight junctions

ExoS

Which Pseudomonas effector molecule enhances eicosanoid synthesis

ExoU

Which Pseudomonas effector molecule functions in the same way as Anthrax?

ExoY

Pseudomonas' Type II secretion system secretes:

Phospholipase C

Exotoxin A

Chitin-binding protein

Elastase

Lipase

When Psuedomonas recognizes an HSL, transcribes two proteins for virulence:

LasA= Protease

LasB= Elastase

Brominated furinone

Has no effect on survival of biofilms, simply makes them vulnerable to antibiotics

Tobramycin

Increases biofilm formation

What type of antibiotics INCREASES biofilm formation

Aminoglycosides