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Phys Pro Section 3 > Sporulation > Flashcards

Sporulation Flashcards

1
Q

What is the causative agent of anthrax?

A

Bacillus anthracis

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2
Q

What is the causative agent of Tetanus?

A

Clostridium tetani

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3
Q

What is the causative agent of botulism?

A

Clostridium botulinum

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4
Q

What is the causative agent of gas gangrene ?

A

Clostridium perfringens

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5
Q

What are the 3 basic components of the endospore?

A
  1. Core
  2. Cortex
  3. Coat
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6
Q

What is the composition of the core? What is there a high level of?

A

dehydrated cytoplasm with NA, ribosomes, enzymes, and HIGH level of calcium dipicolinate

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7
Q

What is calcium dipicolinate thought to confer?

A

Heat resistance properties of the spore

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8
Q

What is the composition of the cortex?

A

modified peptidoglycan cell wall layer that is not a highly cross linked as the vegetative cell

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9
Q

What is the composition of the coat? What is it responsible for?

A

Protein layers that are impermeable to most chemicals

- confers chemical resistance

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10
Q

Describe what happens in the 7 stages of sporulation

A
  1. Chromosome condenses to axial filament and septum begins to form
  2. Septum complete and a chromosome is translocated into the forespore
  3. Mother cell septum engulfs the forespore, giving it two outer membranes
  4. Space between the membranes of the forespore is filled with cortex (peptidoglycan)
  5. Spore coat is laid down around outer membrane with proteins made by mother cell
  6. Spore develops resistance properties
  7. mother cell lysis and release of spore
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11
Q

What is the role of FtsZ?

A

Forms a FtsZ ring at both cell poles.

FtsZ ring is formed and septum formation follows.

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12
Q

What is the “master regulator” of sporulation genes? What genes does it act on?

A

Spo0A

transcriptional factor that regulates over 120 genes including those required for chromosomal axial filament and FtsZ ring formation.

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13
Q

What is the DNA translocate involved in septum formation?

A

SpoIIIE

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14
Q

What is the mechanism of SpoIIIE similar to ?

A

translocates chromosome into the forespore compartment by a mechanism similar to plasmid transfer during conjugation.

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15
Q

What is the role of Spo0J and RacA?

A

Bind to the origin of replication region of chromosome (oriC) .
Help to recruit chromosome to the cell pole (by interacting with DivIVA).

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16
Q

What is DivIVA? What is the result of its action

A

anchor protein at cell pole that binds Spo0J and RacA

Binding of RacA to DivIV displaces MinCD and allows for septum formation at the pole

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17
Q

How many sporulation sigma factors are required for this process?

A

5

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18
Q

How many FtsZ rings does the cell contain at the initiation of sporulation?

A

A single medial one

19
Q

Where is SpoIIIE located in the cell?

A

As discrete foci in the membrane

20
Q

Where are Spo0J and DivIVA?

A

DivIVA is located at one pole while Spo0J dynamically relocalizes from pole to pole

21
Q

What is expressed as a result of initiation of sporulation?

A

RacA and FtsZ

22
Q

What happens to the chromosome and the medial FtsZ ring after sporulation is initiated?

A

Nucleotides of chromosomes (one daughter and one spore) remodelled into an axial filament

FtsZ ring relocalizes from midcell to 2 rings, one in each subpolar region via a helical intermediate

23
Q

Where does RacA concentrate? what does it bind to? what is the result? do any other factors assist?

A

Concentrates at OriC and binds to DivIVA which anchors the filament to the poles. Spo0J assists

24
Q

How much of the chromosome is initially trapped in the prespore after septation?

A

30%

25
Q

How does the remaining 70% get into the prespore?

A

SpoIIIE relocalizes to the asymmetric septum and transports the remaining 70% of the chromosome into the prespore

26
Q

What kind of system controls the initiation of sporulation? what needs to be ultimately activated?

A

Phosphorelay system that culminates in the phosphorylation of Spo0A

27
Q

What are the two histadine kinases involved in sporulation initiation? what is the difference between the two

A

KinB (a cell membrane HK that responds to an external signal) and KinA (cytoplasmic HK that responds to internal signal)

28
Q

What happens after KinB and KinA receive signal?

A

They become autophosphorylated

29
Q

Where do KinB and KinA transfer the phosphoryl group to?

A

Spo0F

30
Q

Where does the P go after Spo0F?

A

Spo0B

31
Q

Where does the P go after Spo0B?

A

Spo0A!

32
Q

What are the 3 phosphatases that control the phosphorelay system?

A

RapA RapB and Spo0E

33
Q

What do RapA and RapB dephosporylate?

A

Spo0F-P

34
Q

What does Spo0E dephosphorylate?

A

Spo0A-P

35
Q

What peptide regulates RapB?

A

CSF = Competence and sporulation stimulating factor

- also stimulates genetic competence

36
Q

What regulates RapA?

A

pentapeptide called Phosphatase regulator A

PhrA) peptide (PEP5

37
Q

What are CSF and PEP5 produced by?

A

The bacteria

38
Q

Describe the steps in the regulation of the RapA phosphatase.

A
  1. ComP (membrane HK) receives an unkown competence signal, autophosphorylates and transfers the phosphoryl group to ComA (RR)
  2. ComA-P stimulates the transcription of the rapA-phrA operon
  3. PhrA secreted into periplasm and processed into pentapeptide
  4. PEP5 imported by an oligopeptide permease/ABC transporter system back into the cytoplasm
  5. in the cell, PEP5 inactivates RapA
  6. inactivation of RapA leads to a higher level of Spa0A-P and sporulation is initiated.
39
Q

What happens if a bacteria is mutated in the PhrA genes?

A

PhrA must be processed. In PhrA- mutants, RapA phosphatase activity is very high and sporulation is inhibited

40
Q

What mechanism has been suggested as being responsible for sporulation initiation?

A

Quorum sensing

41
Q

What is the quorum sensing argument?

A

As the population density increases, CSF and PhrA peptide concentrations also increase.

When CSF and PhrA peptides reach a threshold level, sporulation is initiated

42
Q

What is the difference between the CSF threshold for genetic competence and the one for sporulation?

A

CSF threshold level that stimulates genetic competence is lower than that that stimulates sporulation.

43
Q

When does genetic competence occur? When does sporulation occur? (growth phases)

A

Genetic competence happens during early exponential growth phase.
Sporulation occurs at stationary phase of growth

Phys Pro Section 3 (5 decks)

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