Engineering covalent loops in proteins can serve as an on/off switch to regulate threaded topologies

Area of Science:

• Biochemistry
• Structural Biology
• Protein Engineering

Background:

• Protein knots are complex topological structures requiring advanced study techniques.
• Investigating protein knots presents significant in vitro experimental challenges.
• Understanding knot topology is crucial for protein folding and function.

Purpose of the Study:

• To introduce a simplified system for studying protein knots in vitro.
• To investigate the utility of disulfide bridges in manipulating protein topology.
• To analyze the geometric and functional consequences of introducing pierced lasso topologies.

Main Methods:

• Discovery and characterization of pierced lasso bundles (PLB).
• Utilizing disulfide bridges as controllable "on/off" switches for topological states.
• Analysis of crystal structure (PDB code 2YHG) of a de novo designed nucleoside hydrolase.

Main Results:

• Identified PLB as a simplified model for in vitro protein knot studies.
• Demonstrated disulfide bridges enable manipulation of protein topology without altering secondary/tertiary structure.
• Observed inadvertent PL formation in a designed protein structure.

Conclusions:

• PLB offers a tractable system for in vitro protein knot research.
• Disulfide bridges are a viable tool for engineering specific protein topologies.
• Consideration of geometric consequences is vital when introducing disulfide bridges for topological control.