Give the average size (in nm) of a bacterium.............nm
of a bacterial genome:...................nm
of a bacterial genome:...................nm
1000 nm
1*10^6nm
1*10^6nm
a) name the elementt linking the outer membrane to the peptidoglykan:
b) what is the C-terminal residue of this element?
c) why?
b) what is the C-terminal residue of this element?
c) why?
a) Lipoproteine
b) Lysine
c) the terminal NH2 of the Lys residue and the terminal COOH of a Meso-DAP residue from the Peptidoglycan are linked by a peptide bridge.
b) Lysine
c) the terminal NH2 of the Lys residue and the terminal COOH of a Meso-DAP residue from the Peptidoglycan are linked by a peptide bridge.
What is the general structure of outer-membrane proteins?
B-Barrel structure (antiparallel B-strands)
What is the function of the majority of Outer Membrane proteins?
they form diffusion channels for hydrophilic compounds with a molecular mass below 600 Da.
Cite 3 groups of enzymes found in the periplasm:
nucleases
alkaline phosphatases
Beta-lactamases
Cite precisely the molecule (or part of it) from Gram negative bacteria that is responsible for toxic shock:
LipidA
Cite a major component of the cell wall of Gram pos. bacteria that is absent in Gram neg. bacteria:
Teichoic-acids
Cite the chemical groups that make the LPS negatively charged:
Phosphoryl groups in lipidA
cite the mammalian molecule, that act as a sensor for lipidA
Toll like receptor 4 (TLR4)
Cite the molecule(s) which make the backbone of LipidA
Beta(1-6)-linked-hexosamine disaccharide
cite the main molecules of the Mycobacterial Outer Membrane
lipoarabinomannans
arabinogalactane linked to mycolic acids
Protein G:
a) What is it
b) what does it do?
c) cite the bacterium that produces it:
a) What is it
b) what does it do?
c) cite the bacterium that produces it:
a) a protein, which is covalently anchored to the PG. Can be abundant and can form a kind of protective layer.
b)It binds the Fc fragement of antibodies and therefore prevents from being attacked by the innate immune system, because correct opsonization by the Fab fragment of antibodies isn¨t possible
c) Streptococcus
b)It binds the Fc fragement of antibodies and therefore prevents from being attacked by the innate immune system, because correct opsonization by the Fab fragment of antibodies isn¨t possible
c) Streptococcus
Protein A:
a) Cite the bacterium that produce it:
b) where is it localized on the bacterium?
c) what does it do?
a) Cite the bacterium that produce it:
b) where is it localized on the bacterium?
c) what does it do?
a) Staphylococcus
b) It is covalently anchored to the peptidoglycan. (cell wall)
c) It binds the Fc fragement of antibodies and therefore prevents from being attacked by the innate immune system, because correct opsonization by the Fab fragment of antibodies isn¨t possible
b) It is covalently anchored to the peptidoglycan. (cell wall)
c) It binds the Fc fragement of antibodies and therefore prevents from being attacked by the innate immune system, because correct opsonization by the Fab fragment of antibodies isn¨t possible
Make a drawing of the chemical structure of penicillin an in parallel, the structure it miimics. Put an arrow on the critical bond in both strucures:
Antwort
a) Name every PG precursor in the box underneath its structure. put an arrow on the step, which is inhibited by fosfomycin
b) What is the immediate next step?
b) What is the immediate next step?
a)
1.) UDP-N-Acetyl-Glucosamine (UDP-Glc-NAc)
2.) UDP-N-Acetyl-phosphoenolpyruvat
3.) UDP-N-Acetyl-Muramic Acid (UDP-Mur-NAc)
4.) UDP-N-Acetyl-Muramic Acid-Pentapeptide
(UDP-Mur-NAc-Pentapeptide
b) Lipidcarrier undecaprenyl takes a Mur-NAc-Pentapeptide unit and forms a molecule of undecaprenyl Mur-NAc-Pentapeptide (Lipid I).
cite a molecule that can visualize PG assembly by fluorescence microscopy:
vancomycin coupled to fluorescin (Vanco-FL)
Peptidoglycan (PG) assembly: cite the molecule that makes the difference between Lipid I and Lipid II:
Glc-NAc (unit)
What is the key of Vancomycin resistance?
Replacing the Acyl-D-Ala-D-Ala by an Acyl-D-Ala-D-lactic acid. This modification requires only 2 enzymes: VanH pyruvat reductase und VanA ligase.
Vancomycin: draw the structure of the precursor which replaces D-Ala-D-Ala in resistant bacteria
Antwort
Cite the inducer of E.coli Beta-Lactamase synthesis:
Muropeptide, a breakdown product of PG
Why is permease AmpG essential to the synthesis of AmpC?
AmpG internalizes muropeptides into the cytosol, which are breakdown products of the PF. The intrabacterial transcription activator AmpR becomes activated by binding to this muropeptide and starts the transcription of the Beta-lactamase gen ampC.
Mechanistically, what is the difference between a PBP and a Beta-Lactamase:
After formation of penicilloyl enzyme, beta lactamase can rapidly transfer the open Beta-lactam ring onto a molecule of H2O. PBP can`t do this step and stay irreversibly blocked.
Make a drawing of the biochemical reaction of both enzymes ( PBP and Beta lactamase) with a penicillin.
Antwort
Where are Beta-lactamases localized in Gram pos bacteria?
Where in gram neg. ?
Where in gram neg. ?
a) secreted
b) periplasma
Cite the reaction blocked by bacitracin:
Dephosphorylation of undecaprenyl (recycling of undecaprenyl is blocked)
Draw the chemical strucure of penicillin (a),
and after cleavage by Beta-lactamase
and after cleavage by Beta-lactamase
Antwort
Cite the reaction blocked by bacitracin:
Dephosphorylation of undecaprenyl (recycling of undecaprenyl is blocked)
How can the OM be experimentally separated from the IM
Fractionation by floatation of the total membran fraction onto sucrose gradients (Osborne). Using 14C - labelled Galactose, which is exclusively incorporated into lipopolysaccharides (OM)
Why is the alkaline phosphatase only acitve when introduced in the periplasma?
PhoA requires introduction of disulfid bonds to become active. These oxidation can occur in the periplasma, but not in the cytoplasma.
Cite a molecule other than O2 that some bacteria can use as final electron acceptor:
NO3-
What provides the energy fro flagellar rotation a)
What for twitching motility b)
What for twitching motility b)
a) Proton motive force (PMF)
b) ATP
b) ATP
On which side of the plasma membrane (periplasmic or cytosolic) do you expect to find positive charged aa?
Cytosolic (positive inside rule)
What is the reason to suspect that gliding motility makes bacteria rotate on themselves?
Drawing?
Drawing?
the intracellular gliding motor attachs the bacteria to a solid substate and run along a helicoidal cable, which is maybe formed by the actin-like MreB.
which component makes the density of the outer-membrane higher tha the density of the inner-membrane?
Lipopolysaccharide
Cite two types of mammalian cells producing defensins:
Paneth cells and polymorphonuclear leukocytes
Cite the pathway that can export the green florescent protein across the plasma membrane:
Tat-Pathway
What is the function fo TolC in type I secretion?
Forms a periplasmic and outer-membrane channel
Make a drawing of adhesin YadA (a) and make a schematic representation of its traffic from the plasma membrane (b)
Antwort
Here below the structures of different signal peptides. Name the pathways oon the left AND show with an arrow whrere the peptidase cleaves.
Antwort
Cite the main feature(s) of the N-domain of the Sec-signal peptide:
made of 1-10 residues starting with 1-3 positively charged residues
Cite the main funtion of SRP:
recognizes the nascent IMP, stalls the ribosome and brings the nascent protein and the ribosome to SecYEG translocon, after binding to its receptor FtsY.
Make a schematic drawing on an auto-transporter, showing and identifying the different domains:
Siehe Lösungen auf trial test
Cite a protein export system, which also evolved to capture DNA (transformation)
Type II secretion (T2S)
Mutations in the Lol pathway are lethal in Gram neg. nut not in Gram pos. Why?
In gram neg. bacteria, the Lol pathway is important for the transport of lipoproteins, which are needed to attach the outer membrane to the Peptydoglycan. The gram pos. bacteria have no OM.
Cite a secretion pathway, which transports folded proteins across the OM:
Type II secretion (T2S)
What is the function of OMP85 (YaeT)?
OMP85 ensures the proper insertion of porins in the OM. When OMP 85 is not expressed, the porins do not trimerize. Belongs to the BAM-system (beta-barrel assembly machinery)
Where are the unassembled type IV pilins stored?
in a pool of pilins anchored in the inner membrane.
Where ist the signal peptide for type IV pilins cleaved?
in front of their hydrophobic region
Cite the the function of the C-terminal domain of auto transporters:
The c-terminal beta domain inserts into the OM as a Beta-barrel structure that forms a pore. After, the passenger domain inserts into the pore and is translocated to the bacterial surface,
how many acyl chains are added to lipoproteins befor the signal peptide is cleaved off?
2
Give the name of the system that transport lipoproteines from the IM to the OM:
Lol-System
Why is the deletion of this system lethal?
It prevents the attachment of the outer membrane to the peptidoglycan, via the Braun`s lipoprotein.
Cite the protein secretion system that is evolutionary related to competence in Neisseria:
Type II secretion (T2S)
Why is the Fim or Pap adhesin the only pilin subunit that can inserted in position one?
Adhesin has no N- terminal extension, but instead a lectin domain.
How is a Fim or Pap terminator subunit working?
Ìnsertion of a terminator ledas to an arrest in elongation, because no NTE can insert properly in the groove of the terminator.
Cite a secretion pathway, which transports folded proteins across the outer membrane:
Type II secretion
Why do Gram neg. bacteria not have a sortase?
sortases are needed to anchor surface proteins in the PG of Gram + bacteria. In Gram -, surface proteins are anchored in the OM
Cite the molecule that interacts with the sortase-cargo acyl-enzyme complex for PG anchoring:
Lipid II
Show with a detailed drawing how a protein with LPXTG motif is translocated and anchored to the PG:
Skript Seite 72
In Gram+ bacteria, what is the localization of a protein with a N-ter signal sequence and an LPXTG sequence near the C-term?
cell wall, anchored in the PG
What is the funtion of the enzyme "sortase" ?
recognition and cleavage of the LPXTG motif of surface proteins and generation of a acyl enzyme intermediate, which after reacts with lipid II for PG-anchoring.
(After a nucleophilic attack of the free amino group of the pentapeptide from a precursor MurNAc-pentapeptide, the surface protein is incorporated into the cell wall.)
(After a nucleophilic attack of the free amino group of the pentapeptide from a precursor MurNAc-pentapeptide, the surface protein is incorporated into the cell wall.)
Sortas:
a.) cite enzymatic activity (RNAse, lipase...)
b.) Explain 2 functions:
a.) cite enzymatic activity (RNAse, lipase...)
b.) Explain 2 functions:
a.) Transpeptidase
b.) Recognition and cleavage of the LPXTG-motif
generation of a acyl-enzyme intermediate
What is the function of the C-ter hydrophobic domain and +charged tail of surface proteins from Gram + bacteria?
After cleavage of the N-term signal peptide, they retein proteins in the sec pathway.
Cite the molecule that interacts with the sortase-cargo acyl-enzyme complex for PG anchoring:
Lipid II
What is the function of TolC in type I secretion?
forms a outermembrane and pericplasmic channel.
it`s an integral OM-Protein, which is directly linked with the "adapterprotein" of the inner membran and like that, it forms a channel through the periplasma and trought the OM.
it`s an integral OM-Protein, which is directly linked with the "adapterprotein" of the inner membran and like that, it forms a channel through the periplasma and trought the OM.
How can you detect and identify a non-cultivable bacterium in blood?
looking for variable 16S rDNA flanked by conserved regions, Amplification by PCR and comparison with a sequence database allows to identify the bacterium.
Cite precisely the target of amnioglycoside:
accessible regions of polyanionic 16S RNA on the 30 S Ribosome, notably the A site for aminoacyl t-RNA
How long (approximately) does it take to synthesize a 60kDa protein (in minutes)?
0.5 min
What is the function or activity of the target of quinolones?
introduction of supercoils, which facilitate the packing of DNA but also local unwinding. Essential for cell viability
a.) Cite the target of sulfonamides (sulfanilamides):
b.)cite the main damage of its activation:
b.)cite the main damage of its activation:
dihydropteroat synthase
blocks the folic acid synthesis
blocks the folic acid synthesis
a.) From which molecule does the -CH3 group of dTMP originate?
b.) Cite an antibiotic which blocks the synthesis of this molecule:
b.) Cite an antibiotic which blocks the synthesis of this molecule:
a.) N^5, N^10-Methylene-Tetrahydrofolate
b.) Trimethoprim
b.) Trimethoprim
Bild A/B:
a.) What is the difference beween A und B?
b.) Cite the enzyme that convert B to A
c.) Cite a group of antibiotics that inhibits this enzyme
a.) What is the difference beween A und B?
b.) Cite the enzyme that convert B to A
c.) Cite a group of antibiotics that inhibits this enzyme
a.) A: DNA with supercoils, B: relaxed DNA
b.) DNA-Gyrase
c.) Quinolones
b.) DNA-Gyrase
c.) Quinolones
a.) Cite the end-product of the pathway sulfonamides inhibit:
b.) Cite the main function of this end product:
b.) Cite the main function of this end product:
a.) N^5,N^10-Methylene -Tetrahydrofolate
b.) N^5,N^10-Methylene-Tetrahydrofolate acts as a CH3 group donor for dUMP. dUMP is by this methylation converted into TMP, which is important for DNA synthesis.
b.) N^5,N^10-Methylene-Tetrahydrofolate acts as a CH3 group donor for dUMP. dUMP is by this methylation converted into TMP, which is important for DNA synthesis.
Write the reaction catalyzed by CT-A:
NAD+X pfeil nach rechts ADP-R-X + nicotinamide
What is the effect of the inactivation of the taret of CT-A?
Inhibition of the conrol effect, adenylat cyclase remains activated and cAMP is constanly produced. The enterocytes respond to cAMP by secreting H2O and elektorlytes.
Why are hyper piliated Vibrio strains good recipients for tranduction of the ctxAB genes?
Because the Type IV pilis act as receptors for the CTX phage
How is Cholera Toxin exported? Explain the steps:
1.) CT-A and CT-B are synthesized as pro-peptides in the cytosol.
2.) During the transport through the plasma membrane by the sec pathway, the signal sequence is removed.
3.) CT-A and CT-B fold an assemble in the periplasma. Disulfid bridges are introduced by DsbA.
4.) The holotoxin is now transported across the outer membrane by Type 2 translocon
2.) During the transport through the plasma membrane by the sec pathway, the signal sequence is removed.
3.) CT-A and CT-B fold an assemble in the periplasma. Disulfid bridges are introduced by DsbA.
4.) The holotoxin is now transported across the outer membrane by Type 2 translocon
cite 2 assembly pathways involving bactoprenol:
PG assembly pathway
pili of gram pos bacteria assembly pathway
pili of gram pos bacteria assembly pathway
Kartensatzinfo:
Autor: CoboCards-User
Oberthema: Bioloige
Thema: Mikorbiologie
Veröffentlicht: 14.06.2012
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