Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL6047 - Biofilms and microbiol communities > Biofilm physiology and quorum sensing > Flashcards

Biofilm physiology and quorum sensing Flashcards

1
Q

Chronic bacterial infections involve…

A

the biofilm mode of growth: bacteria withstand the action of the immune system and tolerate the highest deliverable doses of antibiotics.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Pseudomonas aeruginosa

A

16% of nosocomial pneumonia cases
12% of hospital-acquired urinary tract infections
8% of surgical wound infections
10% of bloodstream infections

30% deaths in immunocompromised patients
38% deaths in intubated patients
Associated with 60% of deaths under outbreaks in burn units
Associated with 50% of deaths in the expanding AIDS population

Cystic fibrosis patients are susceptible to chronic infection, which is responsible for high rates of illness and death.
CF is the most frequent severe genetic disease among Caucasians (1:4700).
Chronic wounds (1:100 in Denmark)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

With the aggressive antibiotic regime in CF patients

A

the bacteria are suppressed, however not eradicated in the conductive zone, whereas the remaining respiratory zone is protected from massive biofilm infection for prolonged time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

A minimum of ____ of these problematic wounds are infected with P. aeruginosa.

A

50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

“Quorum Sensing” (QS)

A

a density related process uses cell-cell signaling to coordinate expression of virulence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Principle of QS

A

Bacterial cells increasing in cell density, due to this level of signals increases

Quorum size is reached

The culture makes “a collective decision” and expresses QS controlled target genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Within the steps of Biofilm formation, when is the C-di-GMP and QS processes identified

A

1) Reversible attachment, 2) irriverable attachment, 3) cell proliferation - C-di-GMP identified

4) biofilm maturation, 5) dissolution - QS process identified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain PMN attraction in biofilm formation

A

during biofilm maturation, PMN leukocytes have PMN attraction to the biofilm

The biofilm is surrounded by a PMN shield and outside, necrotic PMN and virulence

When the PMN shield is broken, dissolution occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Overall PMN attraction and destruction causes…

A

collateral damage to the tissue. Inflammation develops.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name some virulence factors involved in pathogenesis, and the genes that cause these to be upregulated

A

elastase
exotoxins
bio surfactants

caused - PqsR, PqsE, RhIR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many genes are regulated by QS

A

200 - 400 depending on the growth conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What activity does OdDHL have

A

Immunomodulatory and vasodilatory activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Quorum sensing controlled production of rhamnolipid by Pseudomonas aeruginosa leads to what?

A

Rapid necrotic killing of PMNs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What can be controlled through the QS systems in P. aeruginosa

A

biofilm development

antibiotic tolerance

virulence

immune shielding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In vitro biofilms seems to produce only minor amounts of what?

A

rhamnolipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are rhamnolipids?

A

PMN leukocyte shield constituent, able to cause rapid lysis in various eukaryotic cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is pyocyanin?

A

a virulence factor that is known to cause death in C. elegans by oxidative stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is PQS?

A

A branch of the QS, a regulatory system

genes encoding signalling molecules of the PQS are upregulated in transacriptome analysis of P. aeruginosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

LDH assay shows ____ caused by rhamnolipid

A

PMN leakage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is Dynorphin A?

A
  • Endogenous κ-agonists belonging to the opioid peptides
  • Modulates pain and stress signals
  • Found in Central Nervous System
  • Contained in various immune cells
  • PMNs produce and release dynorphin at sites of inflammation
  • Found by others to activate pqs, rhamnolipids and pyocyanine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

NAme a dynorphin agonist and what it induces

A

U-50488 -A drug which acts as a highly selective κ-opioid agonist

induces PQS and rhamnolipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

odDHL + PQS synthesis =

A

PMN signal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the relationship of las, rhl and pqs

A

las upregulates pqs which upregulates rhl; pqs links las and rhl systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

pqsA mutant is not able to…

A

up-regulate rhamnolipid production in response to PMN exposure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

HHQ role in QS system

A

serves a a substrate for PQS sysnthesis

promotes PpqsA activity via PsqR to increase itrs own synthesis and PqsE expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

HQNO role in QS

A

Has no effect on P. aeruginosa transcriptome

is a cytochrome inhibator usedin environmental competition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

PQS role in QS system

A

Chelates iron

increases expression of virulence determinants

has negative impact on dentrification

promotes PpqsA activity via both Pqs-R dependant and independant pathways to increase its own synthesis and PqsE expression

28
Q

Contributions of Specific 2-Alkyl-4-Quinolones and PqsE to Quorum Sensing


A

the PQS biosynthetic precursor 2-heptyl-4-hydroxyquinoline (HHQ) triggers a PqsR-dependent positive feedback loop that leads to the increased expression of only the pqsABCDE operon

PqsE is involved in the regulation of diverse genes coding for keyvirulence determinants and biofilm development

PQS promotes2-alkyl-4-quinolones (Aqs) biosynthesis, the expression of genes involved in theiron-starvation response and **virulence factor production via PqsR-dependent and PqsR-independent** pathways

29
Q

What is 2-heptyl-3-hydroxy-4-quinolone

A

PQS

30
Q

does 2-heptyl-4-hydroxyquinoline N-oxide (HQNO) function as a QS signalling molecule

A

No - it doesnt in fluence transcription

31
Q
A
32
Q

Ability of PQS to contribute to gene regulation independent of

A

both its ability to activate PqsR and to induce the iron-starvation response

33
Q

Sputum of CF patients contains what?

A

rhamnolipids

34
Q

What are PMN leukocytes, how do Pseudomonas aeruginosa recognizes and respond to these

A

polymorphonuclear leukocytes

Pseudomonas aeruginosa recognizes and responds aggressively to their presence

response does not involve protective mechanisms, rather it is dominated by an up-regulation of virulence determinants all of which are able to cripple and eliminate eukaryotic cells.

The response is dependent on functional QS systems

35
Q

QS inhibitor can..

A

Restore PMN function

36
Q

Describe the shield model

A
  • Bacteria emerge in a harmless state (no expression of virulence factors)
  • Subsequently they increase in numbers and build biofilms.
  • When quorum size has been attained, the communication system signals and the biofilm microcolonies launch a cocktail of virulence factors including a rhamnolipid based shield which obstructs the function of cellular components of the innate immune system (the PMN Leukocytes)
  • These are killed but bacteria persist.
37
Q

What is biofouling?

A

a major challenge for marine eukaryotes and bacteria can be highly detrimental to marine algae and other eukaryotes

Delisea pulchra is rarely fouled in nature due to the production of secondary metabolites (halogenated furanone compounds).
These compounds have strong biological activity, including anti-QS and antimicrobial properties

38
Q

Secondary metabolites such as the _____ are produces and liberated from specialized vehicles present in the algae Delisea pulchra

A

halogenated furanones

39
Q

Name three compounds that block QS in P. aeruginosa

A

Furanone C-30

Furanone C-56

OdDHL

40
Q

Furanone 30 promotes…

A

Bacterial clearance

41
Q

QS in other Gram-ve bacteria:
CF patient Burkholderia cenocepacia: 4 QS systems

A

Synthase (I) and a receptor (R): CepIR; CciIR systems

Burkholderia Diffusible Signal Factor (BDSF)-based system RpfFBC,

non-ribosomal peptide synthetase-like cluster ham

CepI involved in biofilm formation, protease production, and virulence, as well as an interplay among the Acyl Homoserine Lactone (AHL) systems CepIR and CciIR and the BDSF-based system

diketopiperazines (DKP) inhibit CepI in vitro, impairing the ability of B. cenocepacia to produce proteases, siderophores, and to form biofilm

42
Q

What does DSF stand for and features

A

Diffusable signal factors

DSF is a cis-unsaturated fatty acid first described in plant pathogen Xanthomonas campestris. cis-11-methyl-dodecenoic acid

Produced by bacteria Burkholderia cenocepacia (BDSF), P. aeruginosa (CDA): regulate virulence, biofilm formation, antibiotic tolerance

Autoinducer of biofilm dispersion of P. aeruginosa and other species

Involved in interspecies signalling that modulates bacterial behaviour

43
Q

Removal of established P. aeruginosa biofilms can be done using what?

A

cis-decenoic acid (CDA) combined by antimicrobial treatments

44
Q

DSF synthesis involved what?

A

RpfF: an enoyl coenzyme A (CoA) hydratase and

RpfB: a long-chain fatty acyl CoA ligase

45
Q

Different sensor kinases involved in DSF or BDSF perception in diverse bacteria

A

two-component signal transduction system:

RpfC- sensor kinase

RpfG - response regulator

46
Q

Signals of the DSF family play a role in..

A

interspecies and inter-kingdom signalling.

47
Q

Bacteria need to exit the highly energy-demanding QS maximal activation phase during _____

A

the post-quorum phase

48
Q

QS signal turnover systems are…

A

one of the QS exit mechanisms most frequently identified in bacteria

49
Q

Strains belonging to _______ can rapidly degrade DSF

A

Bacillus, Paenibacillus, Microbacterium, Staphylococcus and Pseudomonas

50
Q

Use _____ to turnover DSF-type QS signals

A

RpfB homologs (fatty acyl CoA ligase)

51
Q

Diketopiperazine inhibitors

A

Inhibit CepI synthase

Cyclic dipeptides also called 2,5-diketopiperazines, are the smallest cyclic peptides frequently found in nature

Secondary metabolites produced by bacteria (90%); fungi, plants and animals

cyclic organic compounds in which the two nitrogen atoms of a piperazine 6-membered ring form amide linkages.

dipeptidyl peptidases, cleave terminal ends of proteins to generate dipeptides, naturally cyclize to form CDPs.

52
Q

Gram Positive QS: Peptides

A

Gram positive QS is exciting because most are pathogens

The QS system is encoded by the global regulatory locus Agr (accessory gene regulator)

The Agr locus encodes a two-component signalling pathway, consisting of two divergent operons – controlled by the promoters P2 and P3

Operon P2 encodes 4 genes; AgrA, AgrB, AgrC and AgrD

53
Q

AgrD encodes

A

a precursor of the AIP

54
Q

AgrB encodes

A

a transmembrane protein responsible for processing and secretion of the AIP.

55
Q

AgrC and AgrA…

A

form structures homologous to a classical two component signal transduction system

56
Q

AgrC is a…

A

membrane sensor, its N-terminal region is the sensor domain containing a binding site for AIP

57
Q

AgrA the response regulator is phosphorylated by ____ causing up regulation of the _____

A

AgrC

P2 and P3 promoters (auto induction)

58
Q

Promoter P3 regulates

A

the transcription of RNAIII and δ hemolysin

59
Q

An increase in RNAIII levels leads directly or indirectly to…

A

…a rise in numerous factors and induces the expression of the P2 promoter

60
Q

AIP Structure

A

AIP’s have between 7 and 9 amino acids, they all share a common central cysteine located 5 amino acids from the C terminal.

The C terminal amino acid forms a catalytic thioester bond with the sulfhydryl group of the conserved cysteine (macrocycle)

2 to 4 (depending on species) amino acids typically form the tail (exocycle) of the peptide.

AIP’s are highly polymorphic and fall into 4 major groups depending on their activation with AgrC.

61
Q

QS principles

A

Cell-to-cell signalling systems composed of 2 genes,

I gene encodes an autoinducer synthase and ER gene encodes a transcriptional activator protein (R-protein)

AI synthase = responsible for synthesis of AI molecule, which crosses the cell membrane

With inceasing cell density intracellular AI conc reaches threshold and AI binds to transcriptional activator

The complex R-protein/AI activates the expression of spoecific target genes

62
Q

What is the master QS regulator?

A

LasR

63
Q

What 2 systems do you need foe the rhll system to be activated

A

The Las and the Pqs system

64
Q
A
65
Q

What else is the Pqs system involved in?

A

Iron metabolism

66
Q
A

BIOL6047 - Biofilms and microbiol communities (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions