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An enzyme's metal preference evolves through redox modulation driven by the cofactor's secondary coordination sphere.
E S Mackenzie1, K M Sendra1, A Baslé1
1Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
Molecular Biology and Evolution
|February 13, 2026
Summary
Evolution of metalloenzymes like iron or manganese dependent superoxide dismutase (SodFM) involves changes in metal preference. This study shows redox tuning by the secondary coordination sphere drives SodFM metal preference evolution.
Area of Science:
- Biochemistry
- Evolutionary Biology
- Enzymology
Background:
- Protein evolution involves changes in metal cofactor preference in metalloproteins.
- The iron or manganese dependent superoxide dismutase (SodFM) family exhibits diverse metal preferences, with documented shifts during bacterial adaptation.
- Understanding the molecular basis of metalloenzyme metal preference is crucial for explaining evolutionary adaptability.
Purpose of the Study:
- To investigate the underlying properties of metal-binding sites that control metalloenzyme metal preference.
- To elucidate how enzymatic metal preference can be reshaped by evolution.
- To link metal oxidation state tuning to evolutionary metal preference changes in SodFMs.
Main Methods:
- Analysis of spectral features of bound iron or manganese to assess redox properties.
- Systematic analysis of metal oxidation states across diverse SodFMs from multiple phylogenetic groups.
- Site-directed mutagenesis of second-sphere residues to probe their role in metal preference and activity.
Main Results:
- A strong correlation was observed between the resting oxidation state of the metal cofactor and the enzyme's catalytic metal preference.
- Mutagenesis of key second-sphere residues demonstrated their coordinated influence on metal-dependent activity and cofactor oxidation state.
- These findings indicate that redox properties are intrinsically linked to metal preference in SodFMs.
Conclusions:
- The evolution of differing SodFM metal preferences across life is driven by the tuning of redox properties via the secondary coordination sphere.
- This mechanism provides insight into how metalloenzymes can adapt to utilize new metal cofactors under evolutionary selection.
- The study highlights the plasticity of metalloenzyme active sites for evolving new metal preferences.
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