ARCIMBOLDO at low resolution: Verification for coiled coils and globular proteins

Area of Science:

• Structural Biology
• Crystallography
• Computational Biology

Background:

• Low-resolution crystallography faces challenges in atomic model determination due to limited experimental data and model bias.
• Accurate phasing and prediction of ubiquitous coiled-coil structures are particularly difficult.

Purpose of the Study:

• To develop and validate a method for solving the phase problem in low-resolution crystallography.
• To enhance the accuracy and reliability of atomic model building from sparse experimental data.
• To improve the phasing and validation of coiled-coil structures at low resolution.

Main Methods:

• Combined fragment location using Phaser with density modification and interpretation using SHELXE.
• Incorporated coiled-coil verification to differentiate correct and incorrect structural hypotheses.
• Enhanced SHELXE tracing for low-resolution data and extended environment assessment.
• Utilized ARCIMBOLDO software with fragment location for non-helical structures.

Main Results:

• Demonstrated efficient coiled-coil phasing and validation in test cases from 3 to 4 Å using ARCIMBOLDO_LITE and ARCIMBOLDO_SHREDDER.
• Successfully applied enhanced SHELXE tracing and verification for low-resolution structure solution, exemplified by the VSR1 structure at 3.5 Å.
• Extended the applicability of ARCIMBOLDO software to low-resolution crystallographic data.

Conclusions:

• The developed method effectively solves the phase problem in low-resolution crystallography, overcoming limitations of scarce data.
• Coiled-coil verification significantly improves the discrimination of correct structural solutions.
• The enhanced ARCIMBOLDO software provides a robust framework for low-resolution structure determination and validation.