Midterm 2 - Notes 6 (Part 5) Flashcards Preview

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Flashcards in Midterm 2 - Notes 6 (Part 5) Deck (33)
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1
Q

What kind of system is VirA?

A

2 component sensor system

- transduction pathway

2
Q

What 2 components make up the sensor system?

A
  1. VirA (sensor kinase)

2. VirG (response regulator, TF)

3
Q

What do VirA and VirG do?

A

They induce transcription of all the Vir genes

4
Q

What is VirA and VirG required for?

A

Transcriptional activation of Vir genes

5
Q

What 3 things are sensed by VirA?

A
  1. Phenolics
  2. pH
  3. Sugars
6
Q

What is sugar sensing mediated by?

A

ChvE

7
Q

What is ChvE?

A

It is a chromosomal virulence gene encoding a sugar binding protein

8
Q

What does sensing results in conformational change lead to?

A

Activation of kinase domain of VirA

9
Q

What does VirA phosphorylate?

A

VirG

- this activates it

10
Q

What does VirG bind to?

A

To the promoters of all Vir-operons

11
Q

How is transcription activated?

A

By binding VirG to RNA polymerase

12
Q

OD

A

Overdrive

13
Q

What 3 things is T-DNA composed of?

A
  1. L border
  2. R border
  3. OD sequence
14
Q

What happens if you delete L?

A

You get transfer

- but the size will vary

15
Q

What go you get if you delete R border, but not L?

A

It abolishes tumourigenesis

16
Q

What enhances T-DNA transfer?

A

OD

17
Q

What are the only 2 elements necessary for T-DNA transfer?

A
  1. R border

2. OD

18
Q

What does VirD1 and VirD2 do?

A

They encode 2 subunits of a site specific nicking enzyme

19
Q

What is the site specific nicking enzyme?

A

Heterodimeric endonuclease

- just cuts one of the 2 strands

20
Q

What does VirD2 covalently bind to?

A

5’ end of nicked DNA

21
Q

What fills in the T-DNA?

A

DNA polymerase

22
Q

What does VirC1 do?

A

It stimulates tumour formation strongly

23
Q

What does VirC1 bind to?

A

Binds to OD region next to the R border

24
Q

What may VirC1 interact with?

A

VirD1/VirD2 complex

25
Q

What does VirC1 provide? (2)

A
  1. Distinction between R and L

2. Ensures unidirectional excision

26
Q

What is VirC1?

A

It is a protein with OD DNA binding abilities

  • role is unclear but it appears to interact and bind to the VirD1 and VirD2 and enhances its efficiency in cutting the DNA
  • it can also guide the ss to the pore
27
Q

What does VirD4 interact with?

A

VirD2/T-DNA

28
Q

What does VirD4 do?

A

Guides T-DNA to secretion pore

- has additional roles in exporting other proteins

29
Q

What does VirB form?

A

An IV secretion pore

- conserved across bacteria

30
Q

What does the VirB/VirD4 complex do?

A

It brings VirD2 to the pore and it then brought outside the bacterial cell

31
Q

Where do VirB proteins span?

A

Inner and outer membrane

- extends into the extracellular space and attaches to the plant plasma membrane

32
Q

What process is ATP dependent?

A

Translocation

33
Q

What drives the process for VirB/VirD4 complex?

A

ATP hydrolysis