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Published on: August 15, 2014
Analysis of 3D structural differences in the IgG-binding domains based on the interresidue average-distance
1Department of Bioscience and Bioinformatics, College of Information Science and Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577 Japa. tkikuchi@is.ritsumei.ac.jp
Amino Acids
|April 24, 2008
Summary
Protein A and G mutants with high sequence identity exhibit distinct 3D structures. New methods, average distance maps (ADM) and p(mu) values, predict folding initiation sites to explain these structural differences.
Area of Science:
- Structural bioinformatics
- Protein folding mechanisms
- Computational biology
Background:
- Staphylococcal protein A and streptococcal protein G IgG-binding domains possess distinct structures: 3 alpha helix bundle and (alpha + beta), respectively.
- Mutants (protein A219 and protein G311) exhibit different 3D structures despite high sequence identity (59%).
Purpose of the Study:
- To elucidate how amino acid sequences with high homology encode distinct three-dimensional (3D) protein structures.
- To identify sequence-based determinants of protein folding initiation sites.
Main Methods:
- Development and application of an average distance map (ADM) based on interresidue distance statistics to predict protein folding properties.
- Conversion of interresidue distance statistics into an effective interresidue potential.
- Calculation of residue contact frequency (p(mu) values) using the effective potential to identify folding initiation sites.
Main Results:
- ADM analysis successfully predicted folding properties.
- p(mu) values correlated with phi values, indicating their role in revealing folding initiation sites.
- Both ADM and p(mu) value analyses successfully predicted folding initiation site information for protein A219 and protein G311.
Conclusions:
- The study successfully identified sequence-based information predicting folding initiation sites.
- ADM and p(mu) value analyses provide insights into the determinants of 3D structural differences between homologous proteins.
- These computational methods can detect structural variations encoded within amino acid sequences.
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