Mechanism of ATP Synthesis

Question 1

What regulates passage of H+ through the F_O membrane?

Answer 1

F₁

Question 2

Which ATP synthase domain faces the matrix?

Answer 2

F₁ ATPase

Question 3

What is the structure of F₁F_O ATPase?

Answer 3

• 3 alpha and 3 beta subunits
• Connected centrally by a gamma, sigma, epsilon subunit

Question 4

How can F₁ and F_O be separated?

Answer 4

By treatment with low salt/urea

Question 5

When F₁ is separated does it have ATPase activity?

Answer 5

Yes

Question 6

When F₁ is separated does it have ATP synthesis activity?

Answer 6

No

Question 7

In F_O what does the addition of oligomycin do?

Answer 7

Inhibits H+ permeability

Question 8

When F_O is separated what happens to its activity?

Answer 8

• High H+ permeability
• No ATPase activity

Question 9

What are the 3 states of beta subunits in ATP synthase?

Answer 9

Tight, Loose, Open

Question 10

What can the loose state of beta ATP synthase subunits bind to?

Answer 10

ADP + Pi

Question 11

What brings about gamma subunit rotation in ATP synthase?

Answer 11

Energy from H+ transport

Question 12

What occurs the gamma subunit is rotated in ATP synthase?

Answer 12

• Tight state becomes the open state
• Loose state becomes the tight state
• Open state becomes the loose state

Question 13

When the subunit which was previously tight is now open in ATP synthase what happens?

Answer 13

ATP is free to leave and ADP and P_i spontaneously form ATP

Question 14

In ATP synthase is energy required for ATP synthesis?

Answer 14

No

Question 15

In ATP synthase is energy required for ATP release?

Answer 15

Yes

Question 16

What mechanism of energy transduction occurs in F₁F_O ATPase?

Answer 16

Indirect

Question 17

Conformational switching from the rotation of gamma subunit against alpha₃beta₃ moves how many degrees in which direction?

Answer 17

120º clockwise

Question 18

What does the c-ring of ATPase rotate with?

Answer 18

Gamma subunit

Question 19

What is the rotation of c-ring in ATPase driven by?

Answer 19

PMF

Question 20

What conserved residue is found in the c subunit of ATPase?

Answer 20

Glutamate

Question 21

What forms the stator of ATPase?

Answer 21

Peripheral stalk

Question 22

Movement of ATP,ADP, and Pi requires how many extra H+ from the PMF?

Answer 22

1

Question 23

What interaction does the conserved Glu form in ATPase C ring?

Answer 23

Salt bridge with Arg residue in alpha subunit

Question 24

What neutralises the Glu-Arg salt bridge in c ring of ATPase?

Answer 24

Protonation of Glu through a channel to P side

Question 25

In C-ring of ATPase what happens when Glu interaction has been neutralised?

Answer 25

Ring rotates so the next non-protonated c-subunit interacts with Arg-residue

Question 26

In C-ring of ATPase how are protons released to the N side?

Answer 26

• C-ring rotates
• At some point the protonated c-subunit aligns with a 2nd channel to the N-side

Question 27

In C-ring of ATPase what does 1 full rotation require?

Answer 27

H+ transfer through each c-subunit