Evolution of structural shape in bacterial globin-related proteins

Area of Science:

• Protein evolution
• Structural bioinformatics
• Phylogenetics

Background:

• The globin protein family displays conserved helix interaction patterns with notable variations.
• Understanding protein structural evolution is key to deciphering functional diversification.

Purpose of the Study:

• To model the evolution of protein structure using a simplified approach based on helix contact changes.
• To investigate the evolutionary dynamics of contact patterns within the globin family.

Main Methods:

• Developed a simplified model of protein structural evolution based on random helix contact changes.
• Utilized a parsimony approach to reconstruct ancestral structural states for 15 bacterial globin proteins.
• Analyzed contact changes and compared phylogenetic reconstructions based on sequence and contact patterns.

Main Results:

• Contact changes occurred more slowly than sequence changes within the globin domain.
• High levels of homoplasy were observed, with no evidence for invariant residue-residue contacts.
• Phylogenetic reconstruction using contact patterns was consistent with, but less resolved than, sequence-based phylogenies.
• No contact pattern convergence was detected between different globin families, suggesting constraints on selection for specific patterns.

Conclusions:

• Protein structure, specifically helix contact patterns, evolves at a slower rate than protein sequence.
• The study provides insights into the evolutionary mechanisms shaping protein structures and suggests limitations on convergent evolution of structural patterns.