Genetic selection designed to stabilize proteins uncovers a chaperone called Spy

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• Optimizing in vivo protein folding is crucial for biotechnology and understanding cellular processes.
• Existing protein folding strategies often require energy cofactors or are limited in scope.
• The discovery of novel chaperones can significantly advance protein engineering and therapeutic development.

Purpose of the Study:

• To develop a novel strategy for discovering and optimizing protein folding in vivo.
• To identify and characterize new chaperone proteins that enhance the stability of unfolded proteins.
• To investigate the structural and functional properties of newly discovered chaperones.

Main Methods:

• Linking protein stability to antibiotic resistance in Escherichia coli to select for improved folding.
• Overproduction and purification of the identified chaperone protein (Spy).
• In vitro biochemical assays to assess chaperone activity (aggregation suppression, refolding).
• Structural analysis of the Spy protein using techniques like X-ray crystallography.

Main Results:

• A novel strategy successfully induced the overproduction of a periplasmic protein, termed Spy, in Escherichia coli.
• Spy was found to increase the steady-state levels of unstable protein mutants by up to 700-fold.
• In vitro studies confirmed Spy as an effective, ATP-independent chaperone that suppresses protein aggregation and aids refolding.
• Structural determination revealed Spy as a unique, cradle-shaped dimer, representing a new class of small chaperones.

Conclusions:

• The developed strategy is effective for discovering novel protein-folding assistants.
• Spy is a novel, energy-independent chaperone with significant potential for protein stabilization and refolding applications.
• Spy represents a new class of small chaperones, expanding the known repertoire of molecular assistants for protein folding.