A systematic case study on using NMR models for molecular replacement: p53 tetramerization domain revisited

Area of Science:

• Structural Biology
• Biophysics
• Crystallography

Background:

• Molecular replacement (MR) using nuclear magnetic resonance (NMR) models is often difficult due to structural discrepancies between solution and crystal states.
• Differences in atomic positions (r.m.s.d.) of 1-2 Å between NMR and crystal structures limit MR success.
• Inaccurate NMR structures, often resulting from insufficient data, further complicate MR.

Purpose of the Study:

• To systematically investigate the utility of NMR-derived models for molecular replacement.
• To assess the impact of NMR model accuracy on phasing X-ray diffraction data.
• To evaluate different types of NMR models for MR applications.

Main Methods:

• Employed NMR search models of varying accuracy to solve 1.5 Å X-ray diffraction data for the p53 tetramerization domain.
• Compared the performance of ensemble NMR models versus single averaged models.
• Investigated the effect of distance-derived B factors on single model performance.

Main Results:

• An approximate correlation exists between NMR search model accuracy and the quality of the molecular replacement solution.
• Ensemble NMR models outperformed single averaged models and showed greater tolerance to model inaccuracies.
• Distance-derived B factors enhanced the performance of single NMR models in molecular replacement.

Conclusions:

• The accuracy of NMR search models directly influences the success of molecular replacement.
• Ensemble NMR models are superior to single averaged models for molecular replacement, offering increased robustness.
• Utilizing distance-derived B factors can improve the effectiveness of single NMR models in crystallographic phasing.