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OMICS > E. coli Biofilms Exam > Flashcards

E. coli Biofilms Exam Flashcards

1
Q

In what direction does the Petricous Flagella move in E. coli?

A

counter clockwise

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2
Q

Where do you find E. coli?

A

Mainly in the Guts of mammals but can be found everywhere

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3
Q

What information is there about Antigen 43?

A
  • There are 50,000 copies per cell
  • Autotransporter
  • Encoded by the flu gene
  • Important for biofilm formation
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4
Q

What are the O2 requirments of E. coli?

A

Faculatative anerobic

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5
Q

What surface proteins does E. coli have that are important for biofilm formation?

A
  • Antigen 43
  • Type 1 Fibriea
  • Curli Fimbria
  • Pili
  • Flagella
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6
Q

What is some information about type 1 Fimbriae?

A
  • Encoded on the fim switch gene
  • 100-500 per cell
  • adheres to the host mannose receptors
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7
Q

What is some information on curli fimbriae?

A
  • Encoded on the csgBADEFG operon
  • Binds to the host fibronectin
  • Polar bond to the surface: part of the irreversible attachment
  • Aggregation: cell surface aggregation good for nutrients
  • Initial attachment
  • Involved in cell-to-cell interactions
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8
Q

What is the F-Pilus? and general information

A
  • type IV secretion system encoded by the tra locus
  • coded on the conjugation plasmid
  • Involved in initial attachment
  • Horizontal gene transfer
  • Conjugative plasmid: contains adhesion factors on mobile genetic elements
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9
Q

Information about the flagella?

A

when flagella concentrations are low the there is upregulation of C-di-GMP

If flagella gene knocked out biofilm formation reduces or doesn’t happen at all

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10
Q

What are important biofilm molecules involved in biofilm structure and EPS in E. coli?

A
  • PNAG
  • Cellulose
  • Colanic acid
  • c-di-GMP
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11
Q

What is the most common pollysacharide in the E. coli EPS?

A

PNAG

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12
Q

What is the structural polysaccharide in E. coli?

A

Cellulose

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13
Q

What is cellulose’s role in E. coli?

A

Structure

Works in tandem with curli fimbriae to create elasticity and morphology of the biofilm shape

Creates baskets with amyloid proteins: aids in aggregation of nutrients

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14
Q

What is colanic acid and how does it affect the biofilm?

A

negatively charged polymer

Creates the capsule of the E. coli

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15
Q

What is dispirsin and what does it do to the biofilm?

A

Prevents electrostatic interactions of the curli fimbraies

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16
Q

What are the Two, Two-component systems in E. coli?

A

RCS system

CPXRA

17
Q

how does the RCS two-component system work?

A

Phosphorelay system: Which mediates biofilm formation

  1. RscC: Sensor kinase: Transfers a phosphate to RcsB via RscD: responds to the surface changes. Regulates the CPS operon which encodes for colanic acid.
  2. RscD: histidine-containing phospho-transmitter domain protein
  3. RcsB: Regulatory protein: activates the RCS system. Acts as an inhibitor in other systems
  4. RcsP: Outer membrane protein: Periplasm
  5. RcsA: positive regulator of wza-wca cluster genes
18
Q

What are all the proteins that are in evolved in the Rcs operon?

A

RcsA, RcsB, RcsC, RcsD, RcsF

19
Q

What does the CpxRA tw0-component system regulate and what does it respond to?

A

Upregulates pilus assembly, motility chemotaxis, and adherence

Senses changes on the surface adapt to the environment and upregulate adhesion molecules. type III secretion systems and cell-to-cell signalling

20
Q

What is the CpxRA to-component system? and what can it lead to?

A

phosphorelay system: can lead to multidrug resistance

  • cpxA: Sensor histidine kinase: It phosphorylates cpxR: has a Mg2++ cofactor. Activated by cell stress.
  • cpxR: cytoplasmic regulator: once phosphorylated it acts a transcription factor and binds to the promoter
  • cpxP: periplasmic protein which inhibits cpxA
21
Q

What are the proteins involved in the cpxRA two-component system?

A

cpxA

cpxR

cpxP

22
Q

What are the four general steps for quorum sensing?

A
  1. synthesis of signal molecules (autoinducers)
  2. excretion of signalling molecules
  3. activate receptors
  4. repression of gene expression
23
Q

What are the two quorum sensing pathways in E. coli?

A

AI-2

AI-1 (AHL)

24
Q

What is AI-2 enzyme in e. coli?

A

Luxs enzyme

25
Q

What are the stages of AI-2 pathway in quorum sensing?

A
  1. AI-2 binds to e-coli receptor
  2. LsrACDB transporter brings the AI-2 in
  3. LrsK phosphorylates the AI-2
  4. The phosphorylated AI-2 prevents the LaskR from repressing the LSR gene.
  5. Lsr gene is expressed
  6. Lsf&Lsg heteroprotein degrade the AI-2
26
Q

What are the proteins involved in the AI-2 pathway of quorum sensing?

A

AI-2

LsrK

LsrR

LsrF

LsrG

27
Q

What is the gene that is activated by AI-2?

A

Lsr operon

28
Q

Does E. coli make AI-1?

A

NO

29
Q

What molecule inhibits the AI-1 pathway?

A

glucose

30
Q

What are the steps of AI-1 in e. coli quorum sensing?

A
  1. AHL binds to the E. coli receptor
  2. AHL is transported into the cell
  3. AHL binds to SdiA
  4. SdiA upregulates YdiV
  5. YdiV upregulates the PAP2 operon: upregulating fimbria production and synthesising PAP X
  6. PAPX binds to and inhibits the flhD promoter, which then downregulates the flagella and fimbriae production increases.
  7. SdiA & YdiV activate the cya and crp genes. CYA produces cAMP and crp produces CAP
  8. cAMP binds to CAP: which in turn binds to the lsrR promoter upregulating the lsr gene.
31
Q

What are the foure host receptors that E. coli commonly binds?

A

Mannose

Amyloid

Fibonectin

Collagen

OMICS (11 decks)

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