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Question 1

What is in the second paragraph?

Answer 1

Molecular chaperones definition.
Not foldases. 
Large and diverse group. 
Most well studied. 
GroE chaperonin GroEL and GroES.

Question 2

How big is GroEL?

Answer 2

Large 57.4 kDa monomer with apparent molecular weight of ~800 kDa.

Question 3

What are GroELs subunits?

Answer 3

14 identical 549-residue subunits in two stacked 7 subunit rings.

Question 4

What activity and affinity does GroEL have?

Answer 4

Weak ATPase activity and strong affinity for non-native proteins.

Question 5

Describe GroES?

Answer 5

Caps one end of the stacked GroES rings in the presence of ATP or ADP with a dome-shaped heptameric ring of 97-residue subunits.

Question 6

What is the height of the complex?

Answer 6

184Å

Question 7

What is the width of the complex?

Answer 7

140Å

Question 8

What does the structure form?

Answer 8

A central chamber which is used as a cage for non-native proteins to fold in.

Question 9

What is in the fourth paragraph?

Answer 9

Reaction cycle.
ATP binding pockets to hydrolyse ATP. 
Occurs simultaneously and drives a conformational change. 
Widens and elongates the chamber.
Can hold a 70kD protein.

Question 10

How does the volume of the central chamber change?

Answer 10

85-175 Å3

Question 11

What is the first step in the reaction cycle?

Answer 11

A ring binds 7 ATP and an improperly folded substrate by association with the hydrophobic areas in the chamber.

Question 12

What is the second step of the reaction cycle?

Answer 12

GroES binds to cap GroEL making a cis and tran ring. Conformational change which buries hydrophobic regions and releases the substrate into the chamber. Also begins to partially unfold the substrate by stretching it, rescuing it from being trapped in a local energy minimum and allowing it to go on to fold into its native state down the folding funnel.

Question 13

What is the third step of the reaction cycle?

Answer 13

Sub rate proteins folds into a better-conformation. Micro-environment prevents non-specific aggregation with other mis-folded proteins.

Question 14

What is the fourth step of the reaction cycle?

Answer 14

In the ~10 s the cis-ring hydrolyses it’s 7 ATP releasing the inorganic phosphate. Removes the gamma phosphate group and reduces the interactions between GroEL and GroES.

Question 15

What is the fifth step of the reaction cycle?

Answer 15

Trans-ring binds 7 ATP and a secondary substrate protein but only ones cic has hydrolysed its ATPs as blocked by conformational linkages.

Question 16

What is the sixth step of the reaction cycle?

Answer 16

Conformational change causes cis-ring to release it’s ADP, GroES and presumably better-folded protein.

Question 17

What happens after step 6?

Answer 17

The two rings turn 180 degrees to switch the trans ring to the cis ring and the cycle begins again.

Question 18

What is in the last paragraph?

Answer 18

7 ATP used per cycle.
~5% are folded into the native state in the first cycle so have to rebind GroEL.
Proteins revisit for maintenance.
Very ATP costly highlights importance of properly folded proteins.

Question 19

What is in the intro (sentence by sentence)?

Answer 19

Correct folding is essential for function.
Protein folding is complex and defined pathways.
Incorrect folding can cause fatal diseases.
Vitally important for correct protein folding so molecular chaperones are recruited.