Lecture 3 - Exopolysaccharides and Membrane Proteins Flashcards
The structure of the cell wall is important to the integrity of the cell. One way to kill bacteria is to:
attack the cell wall, since without it bacteria CANNOT survive
Gram Negative Summary
2 membranes, inner and outer
Peptidoglycan layer is in between the 2
Space between the 2 membranes (IM & OM) is the periplasmic space
Gram Negative bacteria stain PINK/RED in gram stain
Gram Positive Summary
Have a thick layer of peptidoglycan and no outer membrane.
Will stain purple in a gram stain
Most useful antibiotics target the _______ specifically ___________ of the _______
Most useful antibiotics target the MEMBRANE specifically PEPTIDOGLYCAN of the CELL WALL.
Some antibiotics are useful against gram positive bacteria but not gram negative bacteria. Why?
Because the gram negative bacteria have an outer membrane that the drugs cannot penetrate. Other drugs have to be designed to go through the outer membrane of gram negative bacteria.
The CAPSULE is
also called exopolysaccharide capsule or glycocalyx (not good names since not always composed of sugar, sometimes amino acids) USE CAPSULE!
Outside the cell wall,
secreted by the cell,
very defined
the EPS
EPS = extracellular polymeric substance
also called the slime layer or exopolysaccharide (not good names because it is sometimes composed of sugar but NOT always - also proteins or extracellular DNA.)
EPS is not well defined and you cannot see it very well.
It is a matrix that bacterial cells produce that forms a cocoon that shelters and allows bacteria to form a biofilm.
How is capsule stained such that it is visible under microscopy?
The bacteria have a ghostly shade around them which is the capsule. It lies outside of the cell wall and is secreted by the cell, very define, unlike the EPS.
The stains used generally bind to charged particles, but the capsule is NOT charged therefore we cannot stain the capsule specifically. Instead, we use a counter stain to stain everything but the capsule which is why it appears as a ghostly white outline.
What is the main difference between capsule and EPS?
The capsule does NOT detach
What is a biofilm
Biofilms allow cells to attach to a surface. Plaque is a biofilm. Cells attach to a surface (like enamel, epithelial cells, tongue) with a slime layer that allows them to stick, otherwise they would be washed away. In the oral cavity it is ALWAYS a biofilm.
Are tge CAPSULE and EPS necessary for bacterial cell survival?
NOT all Bacteria have capsules or EPS
Both the capsule and EPS are NOT required for the bacteria to grow.
If you mutate bacteria so they cannot produce the capsule, it will grow just as well in a laboratory setting. This is NOT the case with the CELL WALL - bacteria cannot grow without a cell wall!
ALTHOUGH NOT REQUIRED FOR GROWTH, THE CAPSULE IS VITAL IN SURVIVAL. CAPSULES AND SLIME LAYERS ARE HELPFUL IN THAT THEY ARE:
- physical barriers
- chemical barriers
- protect against dessication
- protect from phagocytosis
What are the Functions of the EPS and Capule?
- PHYSICAL BARRIERS
compounds from the environment can’t penetrate capsules and slime layers well - CHEMICAL BARRIERS
some chemicals can’t penetrate the EPS or just get stuck in it - PROTECTION AGAINST DESICCATION
the cell can survive much longer because the capsule and slime layer create a moist microenvironment - PROTECTION FROM PHAGOCYTOSIS
if protected with capsule, cells of immune system can’t really see the bacteria.
The Capsule can be seen as a __________
VIRULENCE FACTOR
What is a virulence factor?
Virulence factors are properties that help the bacteria to cause infection, specifically helping in one or more of the following:
1. colonization
getting into the body through the skin, respiratory tract, etc
- survival
needs to be able to survive in new environment - establishment/multiplication
avoid being detected by the immune system or grow faster than it can be killed - nutrient obtainment
bacteria needs toxins or enzymes that allow it to harm tissues to get nutrients (Ex: breaking down RBC’s)
Why can cells of the immune system not detect bacteria if capsule is present?
Immune cells usually look for the LPS, which will be concealed by a capsule. the bacterial cells outside of the body will grow well without a capsule, but inside the body the capsule is needed or the immune system will see it and attack it.
What is immunoevasion and what aids with it?
Avoiding of the host’s immune response
The capsule aids with immunoevasion.
Viruses are the most abundant organisms on the planet. Viruses gain entry into the body via a surface receptor on the bacteria. What happens if bacteria is covered by a capsule?
The virus won’t see the receptor and can’t penetrate the cell. If bacteria were covered by EPS, virus would have to go through it which would be difficult.
What can disrupt the cell membrane?
Toxins and detergents
What can protect disruption of the cell membrane from toxins and detergents?
Matrix - EPS - endopolymeric substance OR
Capsule provide some protection against both!
Functions of the EPS
true for just EPS not usually for capsule.
- Nutrient source: the matrix can be a food source since it is composed of proteins and sugars.
Example: S. mutans which causes caries, produces a sugar matrix.
Biolfilm is a gel that is very sticky/slimy and it can attach to a surface of other bacteria, creating an aggregation of cells which is more difficult for the immune system to handle.
What bacteria is said to cause caries?
Streptococcus mutans
What is the structure of biofilm?
The EPS forms a biofilm:
Biolfilm is a gel that is very sticky/slimy and it can attach to a surface of other bacteria, creating an aggregation of cells which is more difficult for the immune system to handle.
What is Streptococcus pneumoniae?
Gram Positive Bacteria
Causes upper respirator infections (pneumonia)
Form a slime layer
If colonies from fresh clinical isolates are smooth colonies, what does this indicate?
Presence of a capsule around the bacteria
If you continue reproducing same bacteria with smooth colonies, from plate to plate, they will eventually form rough colonies. What does this mean and why does it happen?
This means that bacteria have lost their capsules.
Smooth - with capsule
Rough - without capsule
In a lab setting, the bacteria no longer need the capsule anymore so they wont make it because it costs them a lot of energy to do so.
Why is it important to use fresh strains in the laboratory w/ regard to virulence factors?
Fresh clinical isolates or fresh strains are critical for studying virulence factors because bacteria tend to modify their need for certain virulence factors when in a lab setting - since they don’t require them and they require much energy to keep them around.
Ex: loss of the capsule
How many capsules can Streptococcus pneumoniae make?
S. pneumonia can produce 90 different polysaccharides to make different capsules.
Cells that are capsulated are __________ if they do not produce a capsule they are ______ because the immune system will easily kill it
VIRULENT
NON VIRULENT
What is the Classic Griffith experiment?
In the 1920’s people were trying to determine if genetic material was protein, DNA/RNA.
Experiment done with Mickey, a mouse.
- If injected w/ rough strain - Mickey lives
(no capsule, non-virulent, detected by immune system and bacteria killed) - If injected w/ smooth strain - Mickey dies
(capsulated, virulent, not detected by immune system) - If injected w/ heat killed smooth strain - Mickey lives
(though capsulated, bacteria was killed with heat so no effect) - If injected with MIX of Rough strain and heat killed smooth strain - Mickey dies
(this means that something was passed from the heat-killed cells into the rough non-capsulated live cells, which killed Mickey)
What was passed from dead to live cells - protein or DNA?
Determine this by adding protease or DNAse to injections
add PROTEASE to this mixture - Mickey still dies
add DNASE to this mixture - Mickey lives
THIS PROVES THAT THE GENETIC ELEMENT IS DNA - NOBEL PRIZE.
What is the thing that allow bacteria to establish itself in the host and cause disease?
Give an example
VIRULENCE FACTOR
Ex: Capsule it helps the bacteria be bale to survive in organisms without being detected by the immune system.
What is specific to EPS?
- nutrient trap (matrix of sugars can be broken down and used for food in times of need)
- attachment to surfaces
- cell aggregation (helps associate multiple bacterial cells)
When you grow bacterial colonies, you swab a sample and streak it on a plate, single cells grown into _____
COLONIES - CFU = colony forming unit
Each colony is millions of cells that started from one cell.
What did the Griffith Experiment Determine?
This classic experiment determined that DNA is the genetic element which is the particle that contains genetic material.
What is Streptococcus pyogenes?
Gram Positive
Causes strep throat, rheumatic fever, puerperal fever.
Produces a capsule (mostly sugar) -
NAG-glucuronic acid - this has the same structure as hyaluronic acid, which is part of the human extracellular matrix. If the human body recognizes S. pyogenes, this means it will attack not just the bacteria but also cells in the body, leading to rheumatic fever.
Graph: Non-capsulated S pyogenes will not kill mice only wild type bacteria protected by capsule do!
Why bacterium contains NAG-glycuronic acid and why is this dangerous?
Streptococcus pyogenes
NAG-glycuronic acid has the same structure as hyaluronic acid, which is part of the human extracellular matrix. If the human body recognizes S. pyogenes, this means it will attack not just the bacteria but also cells in the body, leading to rheumatic fever.
What Is Streptococcus pyogenes Gram and What does it Cause?
GRAM POSITIVE
Causes strep throat, rheumatic fever, puerperal fever.
Does Streptococcus pyogenes produce capsule?
Yes - NAG-glycuronic acid (same structure as hyaluronic acid in human extracellular matrix - dangerous because if visible to immune system - then body will attack invader cells as well as its own - leading to rheumatic fever)
What Is Bacillus anthracis Gram and What does it Cause?
GRAM POSITIVE
Causes severe upper respiratory infection before migrating throughout the body.
Has 2 plasmids: pXO1+ (produces toxin) and pXO2+ (produces capsule)
Capsule is made of amino acid poly-D-glutamic acid (NOT SUGAR)
Does Bacillus anthracis produce capsule?
Yes capsule is made of poly-D-glutamic acid (not a sugar - AMINO ACID)
Which bacteria has 2 plasmids and what is distinct about their functions?
Bacillus anthracis has 2 plasmids
pXO1+ and pXO2 +
pXO1+ produces the toxin
pXO2 + produces the capsule
Who was Ignaz Philipp Semmelweis?
Noticed that rate of childbed fever was 3x higher in dorctor’s wards than nurse’s wards. Women after birth would get childbed fever because in doctor’s wards (student doctors) did not have hand-washing while the nurses used bleach/vinegar solutions. Semmelweis was palced in an asylum for his theory, which made the hospitals look bad.
Nevertheless, HAND-WASHING REDUCED THE MORTALITY RATE TO BELOW 1% AND HELPED KILL BACTERIA STREPTOCOCCUS PYOGENES
In graph of Bacillus anthracis (2 plasmids pXO1+ and pXO2 +) displaying viral load in the lung or spleen.
- Outcome if wildtype has both toxin and capsule and it infects ________________
- What happens if you knock out pXO2+ __________________
- If wildtype has both toxin and capsule and it infects BOTH THE LUNG AND MOVES TO SPLEEN (has BOTH the TOXIN (pXO1+) and the CAPSULE (pXO2+) so it can move to the spleen and not be detected by the immune system.
- If you knock out pXO2+ then the CAPSULE IS GONE however pXO1+ (TOXIN) is still present, therefore you just have establishment in the lung itself but no migration to the spleen (since without capsule, immune system detects it.)
Streptococcus mutans
Gram Positive
ACIDOGENIC - produces acid that causes caries in enamel (@ pH 5.5 and lower).
To stay attached to teeth, it produces EPS made from glucan. EPS makes it harder for saliva to reach bacteria and buffer acid produced. Sucrose (glucose+fructose) is very important for S mutans to produce glucan. When sucrose breaks down to form glucose + fructose, the bond breaks and high energy is produced which allows EPS to be made. Eating sucrose causes greater occurence of dental caries.
What Is Streptococcus mutans Gram and What does it Cause?
Gram Positive
Produces acid that causes caries in enamel (pH 5.5 and <)
Produces EPS made of GLUCANS. (SUCROSE IS CRITICAL FOR THIS!)
Does Streptococcus mutans produce EPS?
Yes - Produces EPS made of GLUCANS. (SUCROSE IS CRITICAL FOR THIS!)
High energy from breakdown of sucrose into fructose and glucose gives the energy necessary for S mutans to produce EPS. Thus eating sucrose causes greater occurrence of dental caries.
Eating sucrose causes greater occurence of dental caries. Why?
Because sucrose is very important for the S. mutans to make its EPS. Sucrose is Glucose + Fructose, breaking the high energy bond of sucrose produces the energy required for S. mutans to produce the EPS.
Which bacteria requires glucans?
On the graph, what happened in rats, if you know out ability to produce glucans.
Streptococcus mutans requires glucans to produce its EPS.
If ability to make glucans is knocked out, the bacteria find it hard to survive. There is still a small bit of caries occurring in no bacteria mutant rats because other bacteria present that cause caries but not to such a level as those in abundance of glucans.
Staphylococcus aureus
Gram Positive
We know it as MRSA - it is Methicillin-resistant Staphylococcus aureus.
It likes high salt concentration, lives in nose and on skin, A lot of strains are drug-resistant. One of the number one causes of non-viral eye infections.
Good at avoiding immune system because it has a polysaccharide on the capsule (poly-N-acetylglucosamine PNAG) which helps it attach to tissues and cells, form biofilm and protect it from our body’s defense.
What Is Staphylococcus aureus Gram and What does it Cause?
Gram Positive
MRSA - it is Methicillin-resistant Staphylococcus aureus. LIKES high salt concentration - lives in nose and on skin.
Has poly-N-acetylglucosamine PNAG polysaccharide on the capsule (helps protect it from immune system)
What is PNAG?
poly-N-glucosamine - a polysaccharide on the capsule which helps attach STAPHYLOCOCCUS aUREUS to tissues and cells, form biofilm, protect it from our body’s defense systems.
On a graph if you knock out the ability of S. aureus to produce PNAG, what happens with regard to microphages in the body?
Microphages are much more effective at attacking S. aureus and killing it. This explains the much lower survival rate of the PNAG mutant
Capsules are helpful in protecting bacteria, but downside is that capsule components can also be:
weakly immunogenic - this means our bodies can recognize parts of the capsule to initiate an IMMUNE RESPONSE
What is a vaccine?
A dead or inactive for of virus, which does not make you sick, but does cause your body to produce antibodies (active immunization)
What is active immunization?
When you get a vaccine which does not make you sick but causes your BODY TO PRODUCE ANTIBODIES.
If you are bitten by a snake, what sort of immunization will help?
PASSIVE IMMUNIZATION
you will be given the antibodies. (
How do you test in the lab if something is a virulence factor (with mice)
Knock it out and compare to wild type. If mutant no longer causes infection, then knocked out factor is virulence factor. You can further try to reintroduce the factor into the mutant and see if it will cause the infection again.
The tree of life is shown to represent what?
how distantly related one organism is from another. They all originated from a common ancestor and evolved from there.
_____ look like bacteria and sometimes grow in colonies like yeast, but in metabolism they are much closer to eukarya than bacteria.
FUNGI
____ are called ancient microbes and are usually found in _____ environments
ARCHAEA are called ancient microbes and are usually found in EXTREME ENVIRONMENTS LIKE HOT SPRINGS - there are No human pathogens within archaea.
Bacterial cell walls have:
psuedopeptidoglycan
Lysoszyme will do what?
break beta 1,4 cross links in peptidoglycan of mainly gram positive bacteria. it will not degrade cell walls of archaea because it has different structure
What is the S layer?
Paracrystalline protein layer Some bacteria (gram positive and negative) and some Arhcaea have a paracrystalline protein layer (s layer)
This s layer is a layer of proteins the cell secretes located outside the cell wall and is attached to the cell wall and functions similarly to the capsule.
It is not well defined among bacteria so it is not good for vaccines.
The S. layer is resistant to lysozymes.
It only allows partial permeability for toxins, and helps stabilize the membrane.
The bacteria may be able to survive without it. It also helps to hide bacteria from the immune system.
The good thing about the membrane is that it is impenetrable - compounds wont leak trough it but the bad thing is —–
it is difficult to get needed compounds through the barrier.
The good thing about the membrane is that it is impenetrable - compounds wont leak trough it but the bad thing is it is difficult to get needed compounds through the barrier. Therefore, you need ……..
MEMBRANE PROTEINS
For a gram negative bacteria, proteins on the inner membrane are _______ and proteins on the outer membrane are _______
inner membrane proteins
outer membrane proteins
Are there outer membrane proteins in gram positive bacteria?
NO but there could be an S layer
What is the S layer specific to?
Some Gram positive and gram negative bacteria.
What are the functions of the MEMBRANE PROTEINS?
- transport of materials from outside into the cell
- some proteins serve as secretion systems - take materials from inside and bring them outside
- Sensing proteins bind molecules from the environment which leads to up regulation or down regulation of certain genes
- proteins can have a role in attachment (to other cells, to teeth, etc..) These proteins are a virulence factor
- Some proteins can anchor the capsule to the cell
- Toxins
- Enzymes
What is a porin?
Found in outer membranes of gram negative bacteria only, they cross the outer membrane a few times, usually produce a 3 barreled channel. The channels (small openings) lead from outside of the cell into the periplasmic space.
Allows compounds to diffuse from high concentration to low concentration.
Not everything can pass through a porin - channels are usually selective by size since porins are small - average sugar can go through it and amino acids. Lysozyme us too large and cant passthrough so this is why gram negative bacteria are resistant to lysozyme. the lysozyme can/t get to the peptidoglycan.
Chloroplasts and mitochondria have their own DNA and probably originated as gram negative bacteria.
Where are porins found?
In the outer membrane of gram NEGATIVE BACTERIA ONLY
Mitochondria and chloroplasts have their own DNA and probably originated as
gram negative bacteria
Where are porins found?
on the outer membrane of gram negative bacteria only
Which bacteria are resistant to lysozyme? Why?
Gram Negative because lysozyme is too large and cannot pass through porins (which are located on the outer membrane of gram negative bacteria)
What do porins allow compounds to do?
pass through them - channels are usually selective by size since porins are small - average sugar can get through it. Lead from outside the cell into the periplasmic space if compounds are small enough they can diffuse through the porin into periplasmic space.
What are transporters?
bring things from the periplasmic space into the cell. There are different types of transport systems.
Uniport, symport, antiport, simple transport, group transport, abc transport, k channel, lactose permease …
Where are transporters located?
on the inner membrane - there are transporters to bring things from the periplasmic space into the cell. There are different types of transport systems.
WHat are the types of transport systems?
Uniport, symport, antiport, simple transport, group transport, abc transport, k channel, lactose permease ...
What uniport transport system?
compounds like potassium transported straight into the cell by itself - often one direction and one compound
What is symport transport system?
if both the ion nad the compound are transported in the same direction
What is antiport transport system?
if the ion goes in one direction and the compound goes in another direction
What is simple transport system?
doesn’t require ATP - compound does not get modified.
Driven by the energy in the protein motive force - requires only a membrane spanning protein. requires no ATP, H+ only
what is group transport system?
requires ATP. compound passes through and as it passes it is modified. Glucose enters through this system.
What is ABC transport?
Seen in a lot of bacteria. Has 3 elements: a protein in the periplasmic space that binds to the substrate, a protein that forms a channel, third protein produces ATP on the inner side of the inner membrane.
What is the k channel?
simple transporter
K binds to receptor and goes in. No ATP needed
what is the lactose permease?
simple transport.
Specific essential membrane protein to transport lactose from outside the cell into the cell
Lactose binds to lac permease and the transporter changes conformation.
Changes uses gradient of H+ towards the cell to transport lactose in the same direction into the cell.
what is group translocation?
an example is glucose and mannose transport. requires atp. sugar gets through the channel where it gets phosphorylated. glucose becomes glucose 6 phosphate when it comes through and can be used for glycolysis
What is a beta barrel?
proteins are beta barrel proteins that cross cellular membrane and act as a pore through which molecules can diffuse
What size molecules do porins allow?
<1500 daltons or 1.5 kDA
typical sugar - couple hundred daltons
amino acid - 120 daltons
lysozyme which cleaves peptidoglycan is about 14.7 kDA so it is active on gram positive not gram negative
where are porins found
in outer membranes of gram neg, mitochondria and chloroplasts
why are mitochondria chloroplast and eukaryotic cells originally from bacteria?
same size of bacteria
have their own dna
look like gram (-) bacteria (inner/outer membrane and porins in outer membrane)
Driven by the energy in the protein motive force - requires only a membrane spanning protein. requires no ATP, H+ only
Simple Transport
Chemical modification of the transported substance driven by phosphoenolypyruvate.
Involves a series of protein. Requires ATP
Group translocation
Periplasmic binding proteins are involved and energy comes from ATP. Needs a substrate, binding protein, a membrane transporter, and ATP hydrolyzing protein.
ABC SYSTEM
what does it mean to be weakly immunogenic?
This means our bodies can recognize parts of the capsule to initiate an immune response
Vaccines come in 2 forms:
active immunization: causes body to produce antibodies
passive immunization: given antibodies directly
What do we want a vaccine to be?
- only targets one species
- we want it to be immunogenic
(initiate production of antibodies and be bale to mound rapid secondary response) - we want it to be safe - don’t actually want it to cause disease in the person you are trying to immunize
- Ideally will fall off after long term protection (booster shorts to extend period of time protected
- Inexpensive
What are booster shots for?
to extend the period of protection time from a vaccine - eventually good vaccine will fall off to not stay around body forever
Why would there not be a vaccine against S mutans thus eliminating dental caries?
Pharmaceutical companies will not fund development of a vaccine that might kill you in an attempt to prevent something that wont kill you - like dental caries
Haemophilus influenzae
colonizes mucosal surfaces in humans and produces 6 different capsules. the original vaccine using capsule was not that effective in provoking aggressive immune response. as a result, the new vaccine (Hib vaccine) couples toxin with it, making it much more immunogenic.
Where does Haemophilus influenzae colonize?
mucosal sufraces in humans
Does Haemophilus influenzae produce capsules?
Yes 6 different capsules
Original vaccine of haemophilus influenzae was not effective in provoking aggressive immune response. How was new vaccine better?
Hib vaccine was bettwer because it coupled toxin with it making it much more immunogenic (initiate production of antibodies and be bale to mound rapid secondary response)
What does streptococcus pneumonia cause?
meningitis which starts off with flu-like symptoms but can actually cause death through the pressure in the lining of the brain (PCV13 is pneumococcal conjugate vaccine - contains 13 different capsules.)
What is PCV13?
PCV13 is pneumococcal conjugate vaccine - contains 13 different capsules.
Against streptococcus pneumonia
What is neisseria meningitidis?
causes meningococcal disease
MCV4 meningococcal conjugate vaccine is another vaccine made of capsules which protects against Neisseria meningitidis
What is MCV4?
MCV4 meningococcal conjugate vaccine is another vaccine made of capsules which protects against Neisseria meningitidis
Toxin based vaccines are those not based on capsules. For example:
DPT vaccine - based on toxins and protects against diphtheria, pertussis, and tetanus. it is a mixture of toxins from 3 different bacteria
What is DTP vaccine?
DPT vaccine - based on toxins and protects against diphtheria, pertussis, and tetanus. it is a mixture of toxins from 3 different bacteria
Theory is that all life started from one cell, a common ancestor and then
one branch became bacteria, one became archaea and eukarya.
Archaea are usually found in what type of environments?
Very extreme environments
Do archaea harm humans?
No archaea do not generally infect humans
What are archaea referred to?
Ancient bacteria.
When NASA sends satellite to look for life on other planets chances are they will find …
archaea
Archaea have pseudopeptidoglycan which is composed of
N-acetylglucosamine and N-acetyltalosaminuronic acid which are linked by Beta 1-3 glycosidic cross link. They are resistant to lysozyme breakdown adn so we cannot break down archaea cells.
What is pseudopeptidoglycan
What are reach are protected by -
What is the difference between cell wall of archaea and bacteria
ARCHAEA - Beta 1,3 glycosisdic cross link, N-acetylglucosamine and N-acetyltalosaminuronic
BACTERIA - Beta 1,4 - glycosidic bonds.
N acteylmuramic acid
What is difference of effect of lysozyme on bacteria vs archaea
Lysozymes can break down the Beta 1,4 bonds of bacterial cell walls but not the Beta 1,3 bonds of archaea cell walls.
What is the S surface layer?
paracrystalline protein layer found in some bacteria and arachea secreted and attached to the outside of the cell wall. Serves same function as cell capsule, under microscope it looks like crystal structure and has partial permeability to toxins, shields from macrophage recognition of cell wall, and provides structural stability.
Why is S layer not good for developing vaccines?
because S layer proteins are poorly conserved between related species
For gram negative bacteria there are both _____ proteins
inner membrane and outer membrane proteins
Inner and outer membrane proteins are present in ________
Gram negative bacteria
Inner and outer membrane proteins are present in gram negative bacteria and may serve to:
- transport (glucose, other nutrients)
- secretion (toxins)
- sensory (receptors, transmit signals into cell to sense cell density in envrionment)
- attachment (to teeth, buccal epithelial cells, this would make these proteins a virulence factor)
- anchor (binds capsule to cell)
- toxins (attack other cells)
- enzymes
Porins are only found in
outer membranes of gram negative bacteria
___ form barrels that allow substances to diffuse through the cell membrane. it lets compounds _____
PORINS
LETS COMPOUNDS ENTER FROM OUTSIDE OF CELL INTO PERIPLASMIC SPACE
FUNCTION OF PORINS
LETS COMPOUNDS ENTER FROM OUTSIDE OF CELL INTO PERIPLASMIC SPACE
Bacterial cells that have an outer membrane are resistant to ______
Lysozymes because they do not pass lyzozyme (too large to pass through the porins)
Since lysozymes cannot reach the peptidoglycan cell wall, they remain where?
STOPPED AT THE OUTER MEMBRANE OF THE GRAM NEGATIVE BACTERIA
LIKE GRAM NEGATIVE BACTERIA, _____ AND _____ ALSO HAVE PORINS IN OUTER MEMBRANE
MITOCHONDRIA AND CHLOROPLASTS
SOME COMPOUNDS LIKE K+ ARE TRANSPORTED STRAIGHT IN THROUGH A
UNIPORTER
SYMPORTER
COMPOUND IS PASSED WITH AN ION (ION DOWN ITS CONCENTRATION GRADIENT AND GOES IN SAME DIRECTION
ANTIPORTER
ION GOES IN DIFFERENT DIRECTION THAN THE COMPOUND
DOESNT REQUIRE ATP BUT DOES USE ION GRADIENT FOR ENERGY, SPECIFICALLY IT USES THE FGRADIENT OF H+ IONS OR PROTON MOTIVE FORCE ___________ AND EX:
SIMPLE TRANSPORT
EX:
K+ TRANSPORTER
LACTOSE PERMEASE
____ IS A SIMPLE TRANSPORTER WHICH USES H+ GRADIENT TO TRANSPORT THE LACTOSE INTO THE CELL IN THE SAME DIRECTION AS THE H_
LACTOSE PERMEASE
REQUIRES ATP, COMPOUND PASSING THROUGH GETS CHEMICALLY MODIFIED. _______ AND EX:
GROUP TRANSLOCATION
EX: GLUCOSE, MANNOSE, FRUCTOSE TRANSPORTER
GLUCOSE GETS PHOSPHORYLATED UDRING THIS PROCESS
PHOSPHOTRANSFERASE SYSTEM
GLUCOSE, MANNOSE, FRUCTOSE TRANSPORTERS
phosphotransferase takes phsophate from phosphoenolpyruvate (PEP) and places on transporeter. Glucose binds transporter and receives the phosphate, becoming glucose-6-phosphate, This is where glycolysis begins
ABC TRANSPORTER: A Periplasm binding protein such as
MALTOSE BINDING PROTEIN sits in periplasmic space. it binds to substrate and brings it to the opening of the channel B. the substrate passes throughout eh membrane-spanning channel, the transporter. On the inner side of the membrane, ATP is hydrolyzed and the substrate enters the inside of the inner membrane.
2 COMMON WAYS OF TRANSPORT OF SUBSTANCES FROM OUTSIDE OF BACTERIA TO INSIDE
- ENTER THROUGH PORIN (which sits in outer membrane)
2. ENTER THROUGH ABC TRANSPORTER (once you’ve arrive in periplasmic space - sits in inner membrane)
Which secretion system produces E coli alpha hemolysin?
Type I Secretion System
Which secretion system produces Bordetella pertussis toxin
Type I Secretion System
What are the components that make up ABC transporter?
- Protein in the periplasmic space that binds to substrate
- protein that forms a channel
- protein that prpduces ATP on the inner side of the inner membrane
Type I Secretion System
This systems structure is like the ABC transporter structure.There is usually a signal sequence at the C terminus of protein which is like “passcode” that allows protine to exit through this system.
Which secretion system structure resembles the ABC transporter structure?
Type I Secretion System
Which secretion system produces Aa leukotoxin and what does this cause?
Type I Secretion System
This leads to localized aggressive or juvenile periodontitis
Type Il Secretion System
This system has a pore in outer membrane and either a Sec or Tat System in the inner membrane. Sec shuttles unformed proteins. The protein binds SecB and SecA, which delivers it to the SecYEG translocase protein. The translocase requires ATP to send unfolded peptide into the periplasmic space.
Tat shuttles folded proteins Ex: for pili to go through type II secretion system
Type IV pili (E.coli, Pseudomonas aeruginosa)
Exotoxin A and phospholipase C (pseudomonas aeruginosa)
Enterotoxin (vibrio colerae)
Polygalacturonate lyase, endoglucanase, alpha amylase (xanthomonas campestris)
cellulase (Erwinia chrysanthemi)
Associated Secretion system with: Type IV pili (E.coli, Pseudomonas aeruginosa)
Type Il Secretion System
This systems structure is like the ABC transporter structure.There is usually a signal sequence at the C terminus of protein which is like “passcode” that allows protine to exit through this system.
Type I Secretion System
This system has a pore in outer membrane and either a Sec or Tat System in the inner membrane. Sec shuttles unformed proteins. The protein binds SecB and SecA, which delivers it to the SecYEG translocase protein. The translocase requires ATP to send unfolded peptide into the periplasmic space.
Tat shuttles folded proteins Ex: for pili to go through type II secretion system
Type Il Secretion System
Associated Secretion system with: Type IV pili (E.coli, Pseudomonas aeruginosa)
Type Il Secretion System
Associated Secretion system with: Exotoxin A and phospholipase C (pseudomonas aeruginosa)
Type Il Secretion System
Associated Secretion system with: cellulase (Erwinia chrysanthemi)
Type Il Secretion System
Associated Secretion system with: Enterotoxin (Vibrio cholerae)
Type Il Secretion System
Associated Secretion system with: Polygalacturonate lyase, endoglucanase, alpha amylase (xanthomonas campestris)
Type Il Secretion System
Associated Secretion system with: Shigella spp - invasion protein
Type Ill Secretion System
Associated Secretion system with: Salmonella spp - Secreted invasion proteins
Type Ill Secretion System
Associated Secretion system with: T-DNA (Agrobacterium tumefaciens)
Type lV Secretion System
Associated Secretion system with: conjugative plasmids
Type lV Secretion System
Associated Secretion system with: Pertussis toxin (Bordetella pertusis)
Type lV Secretion System
Which secretion system could be a system to transport porins into the membrane?
Type V Secretion System
Which is the Autotransporter secretion system?
Type V Secretion System
What are proteins of the autotransporter?
Signal Sequence
Passenger Domain
Transmembrane Domain
What does the TAT system do?
used to export folded proteins into the periplasmatic space
SPECIFIC N-TERMINAL SIGNAL PEPTIDE SEQUENCES TARGET A PROTEIN FOR EXPORT BY THE TAT MACHINERY
TAT SIGNAL PEPTIDES DIFFER FROM THOSE TARGET PROTEIN TO THE SEC MACHINERY
WHAT DOES THE SEC SYSTEM DO?
TRIGGER FACTOR BINDS TO THE PREPROTEIN AS IT LEAVES A RIBOSOME
THE UNFOLDED PROTEIN IS RECOGNIZED AND BOUND BY THE SECB CHAPERON PROTEIN AND DIRECTED OT SECA
ATP HYDROLYSIS PROVIDES THE FORCE TO DRIVE THE PROTEIN THROUGH THE SECYEG TRANSLOCASE INTO THE PERIPLASM
PROTEINS IN TYPE II SECRETION SYSTEM
ENTER PERIPLASMIC SPACE VIA SEC OR TAT SYSTEM AND ONCE THERE PASS THROUGH THE OUTER MEMBRANE VIA A PORE
WHICH SECRETION SYSTEMS USE PORINS?
TYPE II AND V (MAKES ITS OWN)
WHICH SECRETION SYSTEM IS HOMOLOGOUS TO BACTERIAL FLAGELLUM BASAL BODY?
WORKS LIKE SYRING TO INJECT PROTEINS DIRECTLY INTO EUKARYOTIC CELLS
TYPE III SECRETION SYSTEM
WHICH SECRETION SYSTEM IS HOMOLOGOUS TO CONJUGATION MACHINERY OF BACTERIA?
TYPE IV SECRETION SYSTEM
USED TO DELIVER DNA AND PROTEINS FROM CELL TO CELL
WHAT ARE PHA’S
POLY-BETA-HYDROXYALKANOATES AND GLYCOGEN - PRODUCED AS STORAGE POLYMERS WHEN CARBON IS IN EXCESS
POLYPHOSPHATE IS WHAT?
INORGANIC PHOSPHATE IN GLOBULES
COULD BE USED AS A SOURCE OF PHOSPHATE FOR NUCLEIC ACID AND PHOSPHOLIPIDS SYNTHESIS AND ATP
MAGNETOSOMES
INTRACELLULAR PARTICLES OF IRON MINERAL MAGNETITE THAT ALLOW ORGANISMS TO RESPOND TOA MAGNETIC FIELD
GAS VESICLES
GAS FILLED STRUCTURES THAT ARE MADE OF PROTEIN THAT CONFER BUOYANCY IN CELLS ALLOWING CELL TO POSITION ITSELF IN A WATER COLUMN IN RESPONSE TO ENVIRONMENTAL SIGNALS
ENDOSPORES
HIGHLY RESISTANT DIFFERENTIATED BACTERIAL CELL PRODUCED BY A CERTAIN GRAM POSITIVE BACTERIA
HIGHLY DEHYDRATED STRUCTURE THAT CONTAINS ESSENTAL MACROMOLECULES
CAN REMAIN DORMANT INDEFINITELY BUT GERMINATE QUICKLY WHEN THE APPROPRIATE TRIGGER IS APPLIED
ENDOSPORE FORMATION LEADS TO ?
HIGHLY DEHYDRATED STRUCTURE THAT CONTAINS ESSENTAL MACROMOLECULES
______ CAN REMAIN DORMANT INDEFINITELY BUT GERMINATE QUICKLY WHEN THE APPROPRIATE TRIGGER IS APPLIED
ENDOSPORES
____ FORMATION LEADS TO HIGHLY DEHYDRATED STRUCTURE THAT CONTAINS ESSENTAL MACROMOLECULES
ENDOSPORE
PROCESS OF ENDOSPORE FORMATION
VEGETATIVE CELL
SPORULATING CELL
MATURE SPORE
TYPE III SECRETION SYSTEM
This is like a syringe made of a cluster of proteins. The structure is much like the base of the flagella, which shows flagella evolution from a secretion system. Bacteria attaches to target cells and injects its substance directly into the cell - this is very effective as opposed to releasing contents into the environment.
This is like a syringe made of a cluster of proteins. The structure is much like the base of the flagella, which shows flagella evolution from a secretion system. Bacteria attaches to target cells and injects its substance directly into the cell - this is very effective as opposed to releasing contents into the environment.
TYPE III SECRETION SYSTEM
TYPE IV SECRETION SYSTEM
This secretion system looks like a Type I. The genes for the two are totally different but they are structural similar. They may use use Sec and TAT. This is mainly for moving genetic elements like plasmids, or proteins and not used for secreting toxins.
This secretion system looks like a Type I. The genes for the two are totally different but they are structural similar. They may use use Sec and TAT. This is mainly for moving genetic elements like plasmids, or proteins and not used for secreting toxins.
TYPE IV SECRETION SYSTEM
TYPE V SECRETION SYSTEM
This is an autotransporter system. The signal sequence brings the peptide to the Sec transporter. After passing through the inner membrane via Sec, its C-terminus inserts into membrane and forms a beta batterl. N-terminus passes through, and the passenger domain sticks out of channel like a flag, while the beta-domain remains inside the membrane.
Ex: Aae autotransporter protein. If you knock out Aae, the Aa Aae mutant still binds to rats and cows. That means there is another protein involved binding when it comes to those two animals
This is an autotransporter system. The signal sequence brings the peptide to the Sec transporter. After passing through the inner membrane via Sec, its C-terminus inserts into membrane and forms a beta batterl. N-terminus passes through, and the passenger domain sticks out of channel like a flag, while the beta-domain remains inside the membrane.
Ex: Aae autotransporter protein. If you knock out Aae, the Aa Aae mutant still binds to rats and cows. That means there is another protein involved binding when it comes to those two animals
TYPE V SECRETION SYSTEM
TYPE VI SECRETION SYSTEM
Secretion system is from bacteria to bacteria.
Secretion system is from bacteria to bacteria.
TYPE VI SECRETION SYSTEM
