Chaperonin-encapsulation of proteins for NMR

Area of Science:

• Biochemistry
• Structural Biology
• Biophysics

Background:

• Studying aggregation-prone proteins using solution Nuclear Magnetic Resonance (NMR) presents significant challenges due to their inherent instability and tendency to aggregate.
• Chaperonins, such as GroEL, are molecular machines that assist in protein folding, but their application in encapsulating proteins for structural studies is limited.

Purpose of the Study:

• To develop a novel chaperonin-encapsulation system for the structural analysis of target proteins using solution NMR.
• To create a stable molecular cage capable of retaining target proteins in their native conformation under near physiological conditions.

Main Methods:

• Engineered a single-ring variant of GroEL (SR398) with an ATPase-deficient mutation that irreversibly binds co-chaperonin GroES.
• Developed a small GroEL-binding tag to facilitate protein encapsulation within the SR398/GroES cage.
• Performed encapsulation and subsequent steps under near physiological conditions to preserve target protein native conformation.

Main Results:

• Successfully formed a stable SR398/GroES molecular cage capable of encapsulating target proteins.
• Approximately 50% of the formed cages successfully encapsulated target protein molecules.
• The encapsulation efficiency is dependent on the 12-residue tag sequence, indicating broad applicability across various proteins.

Conclusions:

• The novel chaperonin-encapsulation system provides a robust method for isolating and stabilizing target proteins.
• This technique significantly advances the capability to study highly aggregation-prone proteins using solution NMR.
• The system's reliance on a short tag sequence makes it a versatile tool for a wide range of protein targets in structural biology research.