title: Degradation of lignin β-aryl ether units in Arabidopsis thaliana expressing LigD, LigF and LigG from Sphingomonas paucimobilis SYK-6.
abstract: Lignin is a major polymer in the secondary plant cell wall and composed of hydrophobic interlinked hydroxyphenylpropanoid units. The presence of lignin hampers conversion of plant biomass into biofuels; plants with modified lignin are therefore being investigated for increased digestibility. The bacterium Sphingomonas paucimobilis produces lignin-degrading enzymes including LigD, LigF and LigG involved in cleaving the most abundant lignin interunit linkage, the β-aryl ether bond. In this study, we expressed the LigD, LigF and LigG (LigDFG) genes in Arabidopsis thaliana to introduce postlignification modifications into the lignin structure. The three enzymes were targeted to the secretory pathway. Phenolic metabolite profiling and 2D HSQC NMR of the transgenic lines showed an increase in oxidized guaiacyl and syringyl units without concomitant increase in oxidized β-aryl ether units, showing lignin bond cleavage. Saccharification yield increased significantly in transgenic lines expressing LigDFG, showing the applicability of our approach. Additional new information on substrate specificity of the LigDFG enzymes is also provided.
authors: Plant Biochemistry Laboratory, Department of Plant Biology and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.
authors: Ewelina
authors: E
authors: Mnich
authors: Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.|Department of Plant Systems Biology, VIB, Ghent, Belgium.
authors: Ruben
authors: R
authors: Vanholme
authors: Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.|Department of Plant Systems Biology, VIB, Ghent, Belgium.
authors: Paula
authors: P
authors: Oyarce
authors: Department of Biochemistry and DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, WI, USA.
authors: Sarah
authors: S
authors: Liu
authors: Department of Biochemistry and DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, WI, USA.
authors: Fachuang
authors: F
authors: Lu
authors: Department of Plant Systems Biology, VIB, Ghent, Belgium.
authors: Geert
authors: G
authors: Goeminne
authors: Section for Plant Glycobiology, Department of Plant Biology and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.
authors: Bodil
authors: B
authors: Jørgensen
authors: Plant Biochemistry Laboratory, Department of Plant Biology and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.
authors: Mohammed S
authors: MS
authors: Motawie
authors: Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.|Department of Plant Systems Biology, VIB, Ghent, Belgium.
authors: Wout
authors: W
authors: Boerjan
authors: Department of Biochemistry and DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Madison, WI, USA.
authors: John
authors: J
authors: Ralph
authors: Section for Plant Glycobiology, Department of Plant Biology and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.
authors: Peter
authors: P
authors: Ulvskov
authors: Plant Biochemistry Laboratory, Department of Plant Biology and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.|Carlsberg Research Laboratory, Copenhagen, Denmark.
authors: Birger L
authors: BL
authors: Møller
authors: Plant Biochemistry Laboratory, Department of Plant Biology and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.
authors: Nanna
authors: N
authors: Bjarnholt
authors: Section for Plant Glycobiology, Department of Plant Biology and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.|Carlsberg Research Laboratory, Copenhagen, Denmark.
authors: Jesper
authors: J
authors: Harholt
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005818:Genetic Engineering / Q000379:methods; D005947:Glucose / Q000378:metabolism; D008031:Lignin / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D053858:Metabolic Networks and Pathways / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics; D020578:Sphingomonas / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D008031:Lignin; D005947:Glucose
keywords: 
  Sphingomonas paucimobilis
  ; Ligβ-aryl ether; bacteria; biofuel; lignin modification; saccharification yield