How Chaperonins Use ATP to Refold Misfolded Proteins

Subject : Biology

Question:

Which of the following is important for the function of chaperonins as they refold misfolded proteins?

A. They are very rigid, and this rigidity allows them to force misfolded proteins into the correct tertiary structure.

B. They can hydrolyze ATP to power the changes in protein structure.

C. They have a very flexible structure.

D. They can force many simultaneous changes in the structure of a misfolded protein, causing it to refold quickly in a single step.

Expert Verified Solution:

The correct answer is B. They can hydrolyze ATP to power the changes in protein structure.

Chaperonins are a specific class of molecular chaperones that play a crucial role in maintaining cellular function by assisting the folding of newly synthesized or misfolded proteins. Proteins must fold into specific three-dimensional shapes to perform their biological functions effectively. Misfolding can lead to dysfunctional proteins, which can cause diseases like Alzheimer’s and Parkinson’s. Chaperonins help refold these misfolded proteins, preventing cellular damage.

One of the key mechanisms that make chaperonins effective is their ability to hydrolyze ATP. ATP (adenosine triphosphate) acts as a molecular energy currency. Chaperonins utilize the energy from ATP hydrolysis to induce conformational changes in their structure, which allows them to encapsulate misfolded proteins and provide an isolated environment for refolding. This energy-driven process ensures that the misfolded proteins can go through gradual, controlled structural changes, helping them fold correctly into their functional forms.

While chaperonins are flexible enough to accommodate a wide range of misfolded proteins, it is the ATP hydrolysis that powers the structural changes necessary for the protein refolding process. This energy allows the chaperonins to go through a cycle of binding and releasing the target protein, giving it multiple chances to fold correctly. Therefore, ATP hydrolysis is critical for their function, making it the most important feature for refolding misfolded proteins.

Other choices, like the idea that chaperonins are rigid (Option A) or can force a protein to refold in a single step (Option D), are incorrect because protein folding is a highly dynamic and stepwise process. The flexibility of chaperonins (Option C) aids in the process, but it is not as essential as ATP hydrolysis for the actual refolding mechanism.