Lecture 4 - Pili, Fimbriae, and Flagella Flashcards
Genus of bacteria that does NOT have a cell wall
Mycoplasma
Since they don’t have a cell wall, Mycoplasma are resistant to
a lot of antibiotics such as penicillin -
Antibiotics which target cell wall formation (are ineffective against them)
____ Have a size limiation - big molecules cannot pass - very large particles require vesicular transport out of cell
PORINS
If Protein 1 is knocked out of the ABC Transporter, where will the compound be accumulated?
In the periplasm
What does the ABC Transporter stand for?
ATP Binding Cassette
To secrete enzymes or toxins outside of the bacterial cell, bacteria use
secretion systems (I-VI)
What is secretion system VII
only used for microbacteria - recently discovered.
Which secretion systems need porins in order to be active?
System II bacteria secrete preoteins using Sec and TAT system then they must use a porin to get into the cell
System V is an autotransporter - it builds its own porin while it transports its peptide
System VI the outer porin is not a porin but an actual part of the secretion system
if toxin goes through system I and knocks out all the porins in the membrane, will it still be able to secrete?
YES BEcause SYSTEM I DOES NOT USE PORINS
SECRETION SYSTEM I
This system’s structure is like the ABC transporter structure. There is usually a signal sequence at the C-terminus of protein, which is like the “passcode” that allows protein to exit through this system.
This system’s structure is like the ABC transporter structure. There is usually a signal sequence at the C-terminus of protein, which is like the “passcode” that allows protein to exit through this system.
SECRETION SYSTEM I
SECRETION SYSTEM Il
This system requires porins and secretes Pili
This system requires porins and secretes Pili
SECRETION SYSTEM Il
SECRETION SYSTEM Ill
Directly secretes into the cell mammalian cell. Like a syringe, it binds to its target cell and injects its compounds
Directly secretes into the cell mammalian cell. Like a syringe, it binds to its target cell and injects its compounds
SECRETION SYSTEM Ill
SECRETION SYSTEM IV
Some go through Sec or TAT, some go in directly
Some go through Sec or TAT, some go in directly
SECRETION SYSTEM IV
SECRETION SYSTEM V
Juvenile periodontitis, autotransporter, builds its own porin. Signal sequence allows it to go through Sec/Tat of inner membrane. The beta domain forms the barrel part of the porin, while the passenger domain sticks out like a flag
Juvenile periodontitis, autotransporter, builds its own porin. Signal sequence allows it to go through Sec/Tat of inner membrane. The beta domain forms the barrel part of the porin, while the passenger domain sticks out like a flag
SECRETION SYSTEM V
SECRETION SYSTEM Vl
This is like system III but II allows bacteria to move things into mammalian cell - System VI is more for bacteria - bacteria transfer
This is like system III but II allows bacteria to move things into mammalian cell - System ____ is more for bacteria - bacteria transfer
SECRETION SYSTEM VI
Outer membrane vesicles
Lets say toxin gets into the periplasmic space through TAT or SEC. Outer membrane pinches off a vesicle which detaches from the cell. the cell will rebuild the outer membrane.
Which secretion systems are utilized by Pseudomonas (cause of lung infection in people)
Type I, II, III systems) Also OUTER MEMBRANE VESICLES
How do bacteria store excess carbon?
We humans have fat, if you give a person an excess of a carbon it will be converted to fat.
For bacteria, their storage compound is sugar - PHA’s and GLYCOGEN
PHA = poly-beta-hydroxyalkanoates
What is PHA?
PHA = poly-beta-hydroxyalkanoates
Storage polymers in presence of excess carbon. Bacteria store these carbs in granules within the cytoplasm. PHA has same properties as polypropylene so you can make bioplastics out of bacteria!
Bacteria can fix nitrogen - this bacteria produces a plant hormone called oxin (A. brasilense) this oxin helps roots of plants grow bigger.
Bacteria can fix nitrogen - this bacteria produces a plant hormone called _______ which helps roots of plants grow bigger.
oxin (A. brasilense)
What is PHA-Z?
enzyme that breaks PHA into CO2 and water which is food for bacteria. They can use this process in times of starvation
If we grow bacteria in poor media and also knock out enzyme that makes PHA, IT WILL NOT GROW WELL - IF IT STILL HAS THE ABILITY TO MAKE AND USE PHA IT HAS BETTER RATE OF SURVIVAL.
NOT IMPORTANT IN PATHOGENESIS SINCE WE HAVE ABUNDANCE OF NUTRIENTS FOR BACTERIA.
What happens If we grow bacteria in poor media and also knock out enzyme that makes PHA,
IT WILL NOT GROW WELL - IF IT STILL HAS THE ABILITY TO MAKE AND USE PHA IT HAS BETTER RATE OF SURVIVAL.
Polyphosphate is ?
Another element that is vital for bacteria - needed to build DNA
Metal granules in bacteria contain magnetite. Aquatic bacteria use this to tell which direction is up or down, thus orienting themselves. Again not important for pathogenesis in HUMANS.
MAGNETOSOMES
Is PHA IMPORTANT IN PATHOGENESIS
NOT IMPORTANT IN PATHOGENESIS SINCE WE HAVE ABUNDANCE OF NUTRIENTS FOR BACTERIA.
Aquatic bacteria use this to float (buoyancy) for example to stay in surface waters containing more oxygen
GAS VESICLES
This is important for pathogenesis - most organisms in nature can spread themselves in time and space (movement) Bacteria have pili and flagella to spread themselves through space . Trees cannot do this although their seeds can - spreading in time means going to sleep, going into a dormant state until environmental conditions become better. We can’t do that but some animals can hibernate. Plant seeds which are dormant, bacteria have spores.
ENDOSPORES
Usually if conditions are good, replication occurs and you get 2 cells, when conditions are bad, DNA will replicate but will be covered by _________
peptidoglycan and calcium (dehydrated structure)
Only ______ can produce SPORES
GRAM POSITIVE but not all GRAM + do!
High pressure lets you reach a high enough temperature (AUTOCLAVE) in the clinic _____ is required to kill bacteia
60-80 degrees celcius
____ Temperature is used to pasteurize milk
55 degrees
that is why milk spoils eventually - still spores in there
_____ DEGREES WILL KILL VEGETATIVE STATE AND SPORES
120 degrees CELCIUS
Do Bacillus anthracus produces spores?
YES - Gram positive bacteira which is so resilient to environment can be used as bioweapon.
How do we make spores?
put bacteria in unfavorable environment to induce production of spores.
How long can spores last?
Hundreds of years!
EX: tetanus and botulism are both caused by spore making bacteria.
Why are certain cans inflamed
Anaerobic bacteria inside cans produce the gas METHANOL
Clostridium difficile (C. diff) usually doesn’t attack humans because normal flora of the GI tract prevent it from getting out of control. If you take high doses of antibiotics, the normal flora is not there and the spores of C. diff ____
cause an infection. Sometimes that part of intestine must be surgically removed.
If you give a person high doses of antibiotics, ____ can proliferate too much leading to
YEAST
CANDIDIASIS INFECTION in the mouth
It is not enough to use alcohol sanitizers in the clinic because
ehtannol breaks the bacterial cell membrane thus dehydrating the cells but that kills only bacteria - not spores. you need BLEACH to kill spores.
What is needed to kill spores?
BLEACH
What is germination?
When bacteria spores start growing into bacteria in vegetative state
__, ___, and ____ are important for pathogenesis (developing disease)
PILI
FIMBRIAE
FLAGELLA
ALL VIRULENCE FACTORS
Fimbrae means ____ in latin
thread or fiber
Pili means
hairlike
There is a greater number of ____ than ____ (Fimbria,pili,flagella)
there is a greater number of FIMBRIAE than PILI
____ look like a fuzzy coat of hair all over the cell
FIMBRIAE
___ are longer and thicker than _____ and there aren’t as many on the cell
(Fimbria,pili,flagella)
PILI are longer and thicker than FIMBRIAE and there aren’t as many on the cell
Are pili and fimbria formed from different genes?
One a genetic level, FIMBRIAE and PILI are formed from DIFFERENT GENES
Usually genes for fimbriae are on chromosome
Genes for pili could be on plasmid (DNA that replicates separately from chromosome)
What is a plasmid?
DNA that replicates separately from chromosome
Where are genes for pili?
On plasmid (DNA that replicates separately from chromosome)
Where are genes for fimbriae?
On chromosome
The _____ codes for the sex pili
F plasmid
Type 1 pili is
a fimbriae
What is the role of fimbriae
to attach bacteria to host cells (epithelial cells, other bacteria) in addition, because they stick out they are very antigenic. you invoke immune response by injecting just the fimbriae. they are important virulence factors - without them, bacteria cannot colonize/infect - so if you knock out gene that makes fimbriae, you can make bacteria non-virulent
Without fimbriae bacteria cannot
colonize or infect
What is pilin
protein that composes pili
Type 1 pili is an adhesive pili because
it contains receptors at the tip which can bind to host cells.
On our cells we have glycoproteins that are specific to the individual. The ____ receptors located on pili can bind to glycoproteins and adhere to host cell
LECTIN RECEPTORS
Why do people claim that drinking cranberry juice can get rid of UTI?
Idea that the sugar in cranberry juice binds E coli’s pili receptor. this would prevent bacteria from binding to host cells thus stopping UTI. The problem with doing this is therapeutically you must drink a LOTTTTT and so much sugar is problem too
What is a clinical example which uses Type I pili to attach to tissue and cause infection.
N. gonorrhoeae
Sexually transmitted GRAM NEGATIVE DISEASE
N. gonorrhoeae
GRAM NEGATIVE
Sexually transmitted
Doctor’s put white cream (antibiotic) on newborn baby eyelids in case the mother has gonorrhea infection (one of leading causes of blindness in babies)
Pili is antigenic and that is not good news for bacteria because
HOST CELLS CAN RECOGNIZE IT EASILY
How do you counter the antigenicity of PILI?
PILI HAS MUCH GENE/ANTIGENIC VARIATION. If bacteria normally use PilE gene to make pili, bacteria can switch to a different gene, PilS (and there are 19 variations of PilS). This makes it sothat the antibodies we make for PilE will not detect PilS pili.
What is the effect of bacteria switching to use gene PilS instead of PilE?
Bacteria normally use PilE gene to make pili
if they switch to PilS gene, there are 19 VARIATIONS OF PilS - this makes it so that the antibodies for PilE pili will not detect the PilS pili
What happens to virulence capabilities if you continue plating bacteria in the lab?
It will lost virulence capabilities due to mutations and no necessity for using it. Sometimes the loss is due to phase variation.
Recall that to extend pili out of cell, what system do bacteria use?
Type II secretion system
How do bacteria control the pili
To extend pili out of the cell bacteria use the Type II secretion system - Bacteria can control this process by turning on/off the pili gene. They can turn off the secretory protein which will also affect the presence/absence of the pili.
Pili helps produce ______ of dental plaque and helps aggregation with each other and surfaces.
biofilm
Type I pili can cause what
Huge aggregates and produce an EPS. In a test tube you will see huge clump of biofilm , the faster it sinks the more cells you have.
How do bacteria arrive on a surface?
Via gravity or flagella
There are 2 stages the reversible stage and irreversible stage of bacterial attachment to surfaces. Describe both
REVERSIBLE STAGE: when bacteria arrive and detach
IRREVERSIBLE STAGE: when bacterial cell makes a strong connection via the pili with the surface.
Bacteria start producing EPS and more cells form microcolonies.
More bacterial cells arrive (late colonizers) and attach to initial colonizers (have mechanism to form pili) Mature biofilm allows cells to detach adn move to other areas. Surface can be abiotic, biotic, and they can be other bacterial cells
What is the pellicle?
saliva proteins that cover teeth - this is actually what pili attach to, not enamel
If you plate Aa, it will form pili with agar plate. If you continue plating what will happen to bacteria?
They will lose pili and be easily detached (Flp-1 mutant does not form pilus - cannot autoaggregate, cannot form biofilm)
What is the Flp mutant?
No Flp pili - no attachment - no disease
Bacteria forms biofilm and immune system tries to fight back - what is the result of the immune response?
Bone resorption
While bacteria do not actually break down the bone, the resoroption is a good indicator of bacterial infection
What are type IV pili?
Type IV pili can go in and out of the cell wall. It is built from pilin monomers from the base (close to the membrane) and goes outward. Bacteria can either bind or cleave pilin monomers of the cahin so this causes extension and retraction.
What motility do Type IV pili use?
Twitching motility, via occlusion or through saliva
What is Twitching motility?
Type IV Pili are located at one or both poles of the cell. On a semi-solid surface bacteria can stick to a site on the surface and then decrease the pili length thus sliding itself across the surface. One way bacteria can travel throughout the oral cavity is through salive, through contact (occlusion) or through twitching motility
What is conjugative pili
Also known as Sex pili - this pili is extracted from donor bacteria, it binds to the recipient bacteria and pull it is. Pili have receptors of prortein and phages lik to attach to it. So the sex pili is not actually that thick.
Phages can enter the cell when the pili gets pulled in. Type IV F plasmid codes for this pilus. After retraction of the pilus, bacteria cells fuse and conjugate. Conjugation is when they copy and pass plasmids to each other thus conferring resistance.
What are pili made from?
Protein called pilin
Type I pili are actually called
fimbriae
What are lectins?
Receptors that bind sugars on our cells. They bind to glycoproteins on our cells in order to identify them as self
Receptors that bind sugars on our cells. They bind to glycoproteins on our cells in order to identify them as self
Lectins
What is phase variation?
The concept that bacteria have several phenotypes depending on their environment (Ex: loss of virulent factors when in the lab)
Pili are important in binding but are very antigenic, so this is a problem for bacteria. N gonorrhea overcomes this problem how?
By changing the proteins it uses to make the pili.
Usually PilE is used but the bacteria has another subset of genes that make the same protein but slightly modified. The bacteria can switch the genes used to make the pili to PilS genes. This results in different antigenicity so it is difficult for the body to produce sufficient antibodies quickly enough, this is known as ANTIGEN VARIATION
Does Vibrio cholera have a pili?
Yes it allows it to form biofilms in the gut but in the environment, it attaches to plants with a different kind of pilus. Produces 2 different pili types to attach to two different surfaces. ANTIGEN VARIATION
What is an aggregation assay?
faster bacteria can get to the bottom the more aggregates you have
When you grow Pseudomonas aureginosa (GRAM NEGATIVE) it produces
type I pili and forms aggregates with an EPS (floating biofilm)
Biofilm formation is facilitated by
PILI
What are TYPE IV PILI?
Pili that can go in and out, built from bottom up. The pili can be cleaved to start by bringing them inside.
_____ is a movement mediated by TYPE IV pili that go in and out if there is a surface that is semisolid.
TWITCHING MOTILITY
To measure or examine twitiching motility, do what?
put bacteria underneath agar, so that there is plastic below them and agar above them, if they move along the bottom, that is twitching motility
what is standard agar on a plate?
1.5% agar
Sex pilus is also called the
conjugation pili AKA - TYPE IV PILI
What does the F plasmid code for?
Type IV pili
A resistance plasmid can be transferred through
conjugation
Conjugation and movement of plasmids happens a lot inside of ____
biofilm where bacteria are close
The F plasmid codes for the sex pilus. BActeria with this plasmid are DONORS they attack
other bacteria called recipients via the pilus and put it in. They can now transfer the plasmid to the recipient and recipient can become a donor and can for the sex pilus as well.
___ are for moving on semisolid surfaces and are involvved in attachment
PILI
___ are antigenic and conserved and also have a role in attachment. Involved in the movement of bacteria as well.
FLAGELLA
Flagella are encoded by different genes THAN FIMBRIAE AND PILI. How else to they differ structurally?
They are much longer and there are less of them
The flagella could be 50x longer than length of bacteria
Flagella on one side of the cell
SINGLE POLAR
flagella on each end of the cell
BI POLAR
Flagella in tufts
POLAR IOPHOTRICHOUS
Flagella all over
PERITRICHOUS
Ex: E.coli or Salmonella
The flagella system is one of the smallest and most efficient engines ever created. Describe why
The basal body can spin up to 17,000 RPM
The flagella itself can spin up to 1000 rpm
Can go in reverse unlike an engine
Flagella can also stop
Flagella can propel bacteria as fast as 100x their body length per second.
What is the structure of flagella?
40 proteins
BASAL BODY - anchored in the cell wall
ROTOR - part that spins
in the outer membrane are a few rings
the FLAGELLA HOOK binds the flagella to the big basal body
Stator - consisting of MOD A and MOD B proteins
If you knock out the stator (consisting of Mod A & Mod B proteins) will bacteria have flagella?
Yes bacteria will still have flagella - it wont be able to spin, but it will be there and it will still be antigenic.
If you knock out the hook, will bacterium still have flagella?
No will no longer have flagellum if you knock out hook. will no longer be antigenic
Flagellar Synthesis Explain
The inner structure is built first, then the flagellar proteins are squeezed out.
Flagella consists of a filament, hook, and basal body.
The stator is attached to the peptidoglycan layer. Does not orate - each stator has 2 mot b proteins and 2 mot a proteins.
Protons move through the channels in the stator. They bind to mot a protein inducing the first power stroke to move the rotor.
The unbinding of the protonsdrive the second power stroke.
The rotor rotates
Are there rings in the outer membrane of flagella in Gram Positive bacteria?
IN GRAM POSITIVE BACTERIA, WE DON’T HAVE RINGS IN THE OUTER MEMBRANE SINCE THERE IS NO OUTER MEMBRANE
Can flagella change directiON?
Flagella can stop and change direction
ccw forward
cw backward
If there are multiple flagella bacteria can go through a movement called
tumbling in which flagella spin in difgferent directions allowing bacteria to stay in the same place before changing directions.
If the flagella can move cw or ccw it will all go in
one direction
Flagella are important in swimming motility. This differs from twitching in that
twitching occurs on semi solid surfaces .
swimming occurs on liquid surface. if you make an agar plate have more liquid consistency, you can observe bacteria move. In the center of the plate is inoculated with bacteria it will spread outward if they can swim.
If you knock out the flagella and inoculate a plate with bacteria in the center, what will happen
They will stay in the center of the medium since they cannot swim
Do cells within biofilm have flagella?
Cells within biofilm lose their flagella since they don’t need it unless conditions get bacd in which they are forced to move. Under those conditions, some bacteria start producing the flagella.
What is swarming motility?
Mediated by the flagella in a semiliquid surface. Bacteria secrete surfactant, which is a slimy layer that usually contains lipid. It is a kind of soap that they can glide on with the movement of the flagella.
What is surfactant?
Bacteria secrete surfactant, which is a slimy layer that usually contains lipid. It is a kind of soap that they can glide on with the movement of the flagella.
What is gliding motility?
Some gram positive bacteria don’t have flagella they move by gliding motility. It is like swarming but without flagella. They produce surfactant they can glide on.
WHat is phototaxis?
Positive toward light
negative away from light
What is chemotaxis
Positive - move toward where a nutrient gradient is higher
negative - move away from a toxin
MOVE AWAY FROM A TOXIN
NEGATIVE CHEMOTAXIS
MOVE TOWARD WHERE A NUTRIENT GRADIENT IS HIGHER
POSITIVE CHEMOTAXIS
MOVE TOWARD LIGHT
POSITIVE PHOTOTAXIS
MOVE AWAY FROM LIGHT
NEGATIVE PHOTOTAXIS
MOVE AWAY FROM OXYGEN
NEGATIVE AIROTAXIS
What is negative airotaxis?
away from oxygen, important for anaerobic bacteria that can’t tolerate the free radicals generated by oxygen.
Bacteria move toward a gradient through a series of starts and stops. They move in one direction, pause see if they are on the right track, and alter their direction accordingly, This movement is a mixture of
forward movement, and tumbling
sometimes they make errors in the direction of their movement
Some proteins are involved in bacteria’s ability to sense the environment. Proteins on the surface of the bacteria bind to a specific attractant triggering …
signal transduction pathway that will eventually affect the flagella intracellularly to make it rotate in one direction or another.
How do you measure phototaxis?
Classic way to measure phototaxis is to:
- Take a vessel with bacteria and put into tube with something inside, more bacteria will go inside the tube relative to the surrounding environment if there is attraction. If compound in the tube is repellent, cells wont go inside and there will be less bacteria in the area than you would expect.
- If NEUTRAL - bacteria go in and out until the concentration outside and inside are roughly equal
ANOTHER WAY IS THROUGH MICROSCOPY - cover surface of a glass put bacteria in and bind flagella to surface and tag them with antibody if you put in an attractant or repellent flagella will spin a certain way depending on which it is and you can also tag entire bacteria with FLUORESCENT PROTEIN AND WATCH THEM MOVE ALSO
What are axial filaments?
Some flagella are in the periplasmic space and are called endoflagella. When these flagella move, the bacteria move like a corkscrew, this is characteristic of spirochetes. Some spirochete species can be found in the oral cavity (treponema denticola)
ENDOFLAGELLA ARE OFTEN FOUND IN GRAM POSITIVE BACTERIA
Where are endoflagella generally found?
Gram positive bacteria.
Some bacteria move themselves with ____ in the periplasmic space
ENDOFLAGELLA
Endoflagella bacteria have no _____
outer membrane ring section of the stator
EX: SPirochetes are twisted because of their endoflagella - They are found in periodontal disease, T. denticola
Airotaxis
oxygen makes free radicals, anaerobic bacteria move away from oxygen
Phototaxis
moves towards light
chemotaxis
moves from low gradient of nutrients to high gradient
osmotaxis
gradient of osmolarity they can move ot low gradient away from high salt.
twitching motility
occurs on SEMI SOLID 1.5 % AGAR
Swimming motility
occurs on liquified surface. If you use 0.3 % agar - “goo” it is liquidy and can let you view swimming motility. Swimming allows cells to get away from biofilm, though most cells in biofilm don’t have flagella (not needed)
Swarming motility
occurs on semi liquid surface plate on 1.5 % agar that is moist. Bacteria produces a slimy liquid surfactant that allows it to glide across a surface.
What is peritrichous flagella?
Bundled flagella rotate counterclockwise - they tumble when the flagella push apart in different directions thus orienting the bacteria in a different direction. WHen tumbling they essentially hover.
What is unidirectional flagella?
Bacteria propels, stops and reorients, and then propels in a different direction
MAIN PARTS OF FLAGELLA
filament
hook
basal body - where the engine is (made of stator & rotor)
Stator - stationary - provides energy to spin (mot A and mot B)
Rotor - actually spinning component made of 4 rings L ring, P ring, MS ring, C ring
How does flagella work?
- Hook binds the flagella to the basal body
2.
If i knock out stator
bacteria will still have flagella and be antigenic
if i knock out hook
it will not be antigenitc because you lose the antigenic flagella
E coli strain called 015787 very aggressive caused
Taco bell lettuce outbreak
Flagella is built from
the base. so proteins are squeezed through the cell embrane and added to the bottom of the growing flagella
2 rings in the outer membrane are only present in
Gram negative because gram positive has no outer membrane
