Biochemical and structural characterization of enzymes in the 4-hydroxybenzoate catabolic pathway of lignin-degrading white-rot fungi
Eugene Kuatsjah,
Alexa Schwartz,
Michael Zahn,
Konstantinos Tornesakis,
Zoe A. Kellermyer,
Morgan A. Ingraham,
Sean P. Woodworth,
Kelsey J. Ramirez,
Paul A. Cox,
Andrew R. Pickford,
Davinia Salvachúa
Affiliations
Eugene Kuatsjah
Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
Alexa Schwartz
Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA; Advanced Energy Systems Graduate Program, Colorado School of Mines, Golden, CO 80401, USA
Michael Zahn
Centre for Enzyme Innovation, School of the Environment and Life Sciences, University of Portsmouth, PO1 2DT Portsmouth, UK
Konstantinos Tornesakis
Centre for Enzyme Innovation, School of the Environment and Life Sciences, University of Portsmouth, PO1 2DT Portsmouth, UK
Zoe A. Kellermyer
Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
Morgan A. Ingraham
Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
Sean P. Woodworth
Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
Kelsey J. Ramirez
Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
Paul A. Cox
Centre for Enzyme Innovation, School of the Environment and Life Sciences, University of Portsmouth, PO1 2DT Portsmouth, UK
Andrew R. Pickford
Centre for Enzyme Innovation, School of the Environment and Life Sciences, University of Portsmouth, PO1 2DT Portsmouth, UK
Davinia Salvachúa
Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA; Corresponding author
Summary: White-rot fungi (WRF) are the most efficient lignin-degrading organisms in nature. However, their capacity to use lignin-related aromatic compounds, such as 4-hydroxybenzoate, as carbon sources has only been described recently. Previously, the hydroxyquinol pathway was proposed for the bioconversion of these compounds in fungi, but gene- and structure-function relationships of the full enzymatic pathway remain uncharacterized in any single fungal species. Here, we characterize seven enzymes from two WRF, Trametes versicolor and Gelatoporia subvermispora, which constitute a four-enzyme cascade from 4-hydroxybenzoate to β-ketoadipate via the hydroxyquinol pathway. Furthermore, we solve the crystal structure of four of these enzymes and identify mechanistic differences with the closest bacterial and fungal structural homologs. Overall, this research expands our understanding of aromatic catabolism by WRF and establishes an alternative strategy for the conversion of lignin-related compounds to the valuable molecule β-ketoadipate, contributing to the development of biological processes for lignin valorization.
