Evolutionary convergence in lignin-degrading enzymes

Area of Science:

• Evolutionary biology
• Biochemistry
• Mycology

Background:

• Fungal peroxidases are crucial for lignin degradation, a key process in the carbon cycle and biobased industries.
• The evolution of wood-rotting fungi and their ligninolytic enzymes originated in the Carboniferous period.
• Early fungal peroxidases degraded lignin indirectly using metal cations, unlike modern enzymes.

Purpose of the Study:

• To investigate the evolutionary pathways of lignin degradation in fungal peroxidases.
• To understand the molecular changes enabling direct lignin degradation via tryptophanyl radicals.
• To identify instances of convergent evolution in peroxidase evolution within the Polyporales order.

Main Methods:

• Phylogenetic analysis of fungal peroxidases.
• Ancestral enzyme resurrection to reconstruct extinct enzyme functions.
• Biochemical characterization of resurrected ancestral and extant peroxidases.

Main Results:

• Identified the evolution of a surface oxidation site for nonphenolic lignin degradation.
• Demonstrated that this powerful lignin degradation strategy evolved independently in distinct fungal lineages.
• Showcased convergent evolution at the amino acid level in two distant peroxidase lineages.

Conclusions:

• The ability to degrade nonphenolic lignin evolved multiple times independently in fungal peroxidases.
• Ancestral enzyme resurrection provides insights into the molecular mechanisms of enzyme evolution.
• This study highlights convergent evolution as a significant factor in the adaptation of fungi for lignin degradation.