Question

Put the following steps of GroEL-GroES chaperonin function in order, starting with an unfolded polypeptide and ending with a polypeptide in its native conformation

1. A GroEL ring binds an unfolded polypeptide and 7 ATP

2. GroES binds to GroEL, causing a conformational shift and displacing the polypeptide into the cavity

3. ATP is hydrolyzed and the polypeptide, isolated from interfering contact, folds

4. The GroES "cap" dissociates from the GroEl ring

5. ADP and the folded polypeptide and released as ATP and GroEs bind to the other GroEL ring

Answer 1

Concepts and reason

The problem is based on the concept of function of GroEL-GroES chaperonin. For a protein it is very important to efficiently fold into their native form. This is because the unfolded proteins are generally exposed to hydrophobic regions therefore, more prone to aggregation. Molecular chaperones are required for proper folding of many proteins.

Fundamentals

Molecular chaperone is a class of proteins which is specially design to promote folding in other proteins. Some of them are aided for proper protein folding at the time when they are produced and others refold those proteins which are unfolded. They are also known as heat shock proteins because they are more functional at high temperatures.

Chaperonins are molecular chaperones which are active in protein when they are fully synthesized. They are responsible for formation of barrell shaped chamber for protein so that it can be isolated from rest of the cell. in this chamber protein can aggregate and fold more efficiently. The bacterial GroEL-GroES chaperonin system is one of the example of protein folding with the help of chaperonins.

Initially a GroEL ring binds unfolded polypeptide and 7 ATP because it is more effective in binding. After this GroES binds with GroEL along with unfolded polypeptide and 7 ATP to cause conformational shift and displacement of protein to cavity.

In the cavity, hydrolysis of ATP molecules take place and folding of polypeptide occur. After folding of protein, attached GroES dissociates from GroEL ring. In last step, ADP and folded polypeptide released as ATP. Also, other GroEL ring and GroES binds to each other resulting folded protein.

Ans:

The correct steps of GroEL-GroES chaperonin function is as follows: