Characterisation of mutations in GroES that allow GroEL to function as a single ring

Area of Science:

• Molecular Biology
• Protein Folding
• Biochemistry

Background:

• The chaperonin GroEL functions via a two-ring structure, relying on allosteric signals for its reaction cycle.
• A single-ring GroEL mutant (SR1) lacks chaperone activity due to the absence of inter-ring communication.

Purpose of the Study:

• To investigate if mutations in the cochaperonin GroES that reduce its affinity for GroEL can restore function to the non-functional SR1 mutant.
• To explore the functional consequences of altered GroES-GroEL interactions on chaperone activity.

Main Methods:

• Site-directed mutagenesis was employed to create GroES mutants with altered residues at the GroEL contact site.
• The chaperone function of these GroES mutants was assessed in conjunction with the SR1 GroEL mutant.
• Binding affinities between selected GroES mutants and GroEL were quantitatively measured.

Main Results:

• Approximately half of the generated GroES mutants exhibited partial restoration of chaperone function with SR1.
• Two GroES mutants were confirmed to possess a reduced binding affinity for GroEL.
• Certain GroES mutants demonstrated functional compatibility with single-ring GroEL mutants engineered for activity.

Conclusions:

• Reduced GroES affinity for GroEL can partially restore chaperone function to non-cooperative single-ring GroEL mutants.
• This suggests that modulating the GroES-GroEL interaction is a viable strategy for engineering chaperone activity.
• The findings provide insights into the cooperative mechanisms governing the GroEL chaperonin system.