Photocleavable proteins that undergo fast and efficient dissociation

Area of Science:

• Biochemistry
• Molecular Biology
• Optogenetics

Background:

• Photocleavable molecules offer precise, light-dependent control over biomolecular functions.
• Genetically encoded photocleavable proteins (PhoCl1) were previously developed for optogenetics.
• Limitations of PhoCl1 included a slow dissociation rate, hindering some applications.

Purpose of the Study:

• To elucidate the dissociation mechanism of the first-generation photocleavable protein (PhoCl1).
• To engineer improved photocleavable proteins with enhanced performance characteristics.
• To develop variants with faster dissociation and higher contrast ratios for optogenetic applications.

Main Methods:

• X-ray crystallography was used to determine the structures of PhoCl1 in different states.
• Molecular dynamics (MD) simulations provided insights into the dissociation mechanism.
• Structure-guided engineering and directed evolution were employed to create new variants.

Main Results:

• The crystal structures of PhoCl1 revealed key conformational states.
• MD simulations elucidated the molecular basis of protein dissociation.
• Engineered variants, PhoCl2c and PhoCl2f, demonstrated improved contrast ratio and faster dissociation rates, respectively.
• In vitro and cellular assays confirmed the enhanced performance of PhoCl2 variants.

Conclusions:

• PhoCl2 variants represent significant advancements over PhoCl1 for optogenetic applications.
• Faster and more efficient dissociation enables improved control over protein localization and interactions.
• These engineered proteins offer enhanced tools for precise spatiotemporal manipulation in living cells.