Rigid domains in proteins: an algorithmic approach to their identification

Area of Science:

• Structural Biology
• Computational Biology
• Biophysics

Background:

• Proteins can adopt multiple conformations, crucial for their function.
• Identifying conserved structural elements across these conformations is key to understanding protein dynamics.
• Previous methods for identifying rigid domains have limitations in scalability.

Purpose of the Study:

• To develop and present novel computational algorithms for identifying rigid domains directly from atomic coordinates.
• To analyze the deoxy and oxy conformations of the human hemoglobin alpha 1 beta 1 dimer for rigid domains.
• To enable the examination of structural differences in regions complementary to rigid domains across protein conformations.

Main Methods:

• Definition of a rigid domain as a tertiary structure common to multiple protein conformations.
• Numerical identification using sets of residues with invariant distances between alpha carbons across conformations.
• Development of two algorithms utilizing the difference-distance matrix.
• One algorithm finds all rigid domains but is computationally intensive; the second is computationally tractable for large proteins.

Main Results:

• A rigid domain was identified in the human hemoglobin alpha 1 beta 1 dimer, consistent with prior findings.
• The computationally tractable algorithm allows for recursive searching of non-intersecting domains.
• The method facilitates alignment of different protein conformations by superimposing identified rigid domains.

Conclusions:

• The developed algorithms provide an efficient means to identify rigid domains from atomic coordinates.
• This approach enables detailed comparison of protein structures by focusing on regions outside conserved rigid domains.
• The findings contribute to a deeper understanding of protein conformational changes and their functional implications.