Crystallophore: a versatile lanthanide complex for protein crystallography combining nucleating effects, phasing...

Area of Science:

• Biophysics
• Structural Biology
• Crystallography

Background:

• Macromolecular crystallography faces challenges in obtaining high-quality crystals and solving the phase problem for large biomolecules.
• Existing methods often struggle with difficult-to-crystallize proteins.

Purpose of the Study:

• To introduce a novel lanthanide complex family, "crystallophores" (Xo4), designed to address key bottlenecks in macromolecular crystallography.
• To evaluate the efficacy of a specific terbium complex, Tb-Xo4, in facilitating crystal formation and phase determination.

Main Methods:

• Synthesis and characterization of the Tb-Xo4 crystallophore.
• Co-crystallization experiments with various proteins.
• Structure determination using X-ray diffraction.
• Luminescence-based detection of protein/Tb-Xo4 co-crystals.

Main Results:

• Tb-Xo4 demonstrated potent nucleating properties, yielding well-diffracting crystals for eight proteins.
• The terbium atom in Tb-Xo4 provided excellent phasing power for structure determination.
• Two previously unknown protein structures were determined using this method.
• Luminescence allowed for easy identification and discrimination of protein/Tb-Xo4 co-crystals.

Conclusions:

• The Tb-Xo4 crystallophore effectively addresses major challenges in macromolecular crystallography, including crystal nucleation and phase problem solving.
• This terbium complex offers a dual advantage for biocrystallography, promoting crystallization and enabling structure determination.
• Tb-Xo4 represents a promising new tool for advancing structural biology research.