The origin of lignin biodegradation occurred in the late Carboniferous, 300 million years ago, with the appearance of the first ligninolytic peroxidase in the common ancestor of Agaricomycetes. These enzymes would have provided to the first ligninolytic fungi the ability to attack the lignocellulosic biomass of vascular plants, enabling carbon recycling in land ecosystems.
In a recent article published in Biotechnol Biofuels, the group led by Angel Martínez from CIB, with participation of Iván Ayuso-Fernández and Francisco Javier Ruiz-Dueñas, has recreated the subsequent evolution of ligninolytic peroxidases in Polyporales, a basidiomycete order that appeared near 150 million years ago and where most extant wood-rotting fungi are included. To this end, the main intermediates forming the evolutionary pathway that led to the most efficient ligninolytic peroxidases currently existing in nature have been reconstructed and resurrected. The structural-functional study of these ancestral peroxidases has provided insight into how they acquired the ability to degrade lignin and how this ability improved over time due both to the successive appearance/disappearance of catalytic sites in their molecular architecture, and to their adaptation to the acidic conditions under which ligninolysis occurs in nature.
This study demonstrates that the changes in catalytic activity and stability experienced by these enzymes over the last 150 million years, from the Jurassic to date, has represented an evolutionary exploration in search of the most efficient ways to degrade the lignin polymer. Moreover, it provides ancestral enzymes with a potential biotechnological interest (because of their stability and potential evolvability) for the sustainable production of fuels and chemicals in a biomass-based economy.
Reference: Experimental recreation of the evolution of lignin-degrading enzymes from the Jurassic to date. Iván Ayuso-Fernández, Angel T. Martínez and Francisco J. Ruiz-Dueñas. Biotechnol. Biofuels, 2017, 10:67. doi: 10.1186/s13068-017-0744-x