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The structure and evolution of alpha/beta barrel proteins
1Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802, USA.
Summary
The alpha/beta barrel enzyme family, comprising 10% of known enzymes, likely evolved from a single ancestor. This ancient origin explains their diverse functions and challenges in identifying sequence homology.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Alpha/beta barrel domains are prevalent in enzymes, accounting for approximately 10% of all known enzyme structures.
- This protein family exhibits remarkable functional diversity, catalyzing a wide range of reactions, making it a key target for protein engineering.
Purpose of the Study:
- To investigate the evolutionary history of the alpha/beta barrel enzyme family.
- To present arguments supporting the divergence of all members from a common ancestral molecule.
- To explore the relationship between chemical mechanisms and evolutionary pathways.
Main Methods:
- Analysis of enzyme structures and functions.
- Comparative sequence analysis to infer evolutionary relationships.
- Hypothesis testing regarding evolutionary divergence and convergent evolution.
Main Results:
- Evidence suggests that all members of the alpha/beta barrel enzyme family originated from a single common ancestor.
- The lack of strong sequence homology indicates a very ancient origin for this ancestral molecule.
- Convergent molecular evolution is proposed to occur when a single energetically favorable pathway exists for a chemical reaction.
Conclusions:
- The alpha/beta barrel enzyme family shares a common, ancient ancestor, explaining its functional diversity.
- Understanding the evolutionary history is crucial for protein engineering efforts.
- The concept of convergent evolution is linked to the inherent constraints of chemical reaction pathways.