title: Identification of grass-specific enzyme that acylates monolignols with p-coumarate.
abstract: Lignin is a major component of plant cell walls that is essential to their function. However, the strong bonds that bind the various subunits of lignin, and its cross-linking with other plant cell wall polymers, make it one of the most important factors in the recalcitrance of plant cell walls against polysaccharide utilization. Plants make lignin from a variety of monolignols including p-coumaryl, coniferyl, and sinapyl alcohols to produce the three primary lignin units: p-hydroxyphenyl, guaiacyl, and syringyl, respectively, when incorporated into the lignin polymer. In grasses, these monolignols can be enzymatically preacylated by p-coumarates prior to their incorporation into lignin, and these monolignol conjugates can also be "monomer" precursors of lignin. Although monolignol p-coumarate-derived units may comprise up to 40% of the lignin in some grass tissues, the p-coumarate moiety from such conjugates does not enter into the radical coupling (polymerization) reactions of lignification. With a greater understanding of monolignol p-coumarate conjugates, grass lignins could be engineered to contain fewer pendent p-coumarate groups and more monolignol conjugates that improve lignin cleavage. We have cloned and expressed an enzyme from rice that has p-coumarate monolignol transferase activity and determined its kinetic parameters.
authors.affiliation: Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Saunia
authors.initials: S
authors.lastname: Withers
authors.forename: Fachuang
authors.initials: F
authors.lastname: Lu
authors.forename: Hoon
authors.initials: H
authors.lastname: Kim
authors.forename: Yimin
authors.initials: Y
authors.lastname: Zhu
authors.forename: John
authors.initials: J
authors.lastname: Ralph
authors.forename: Curtis G
authors.initials: CG
authors.lastname: Wilkerson
mesh_terms: D000107:Acetylation; D000217:Acyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D003373:Coumaric Acids / Q000737:chemistry* / Q000378:metabolism; D015870:Gene Expression; D007700:Kinetics; D008031:Lignin / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011422:Propionates; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D003373:Coumaric Acids; D010940:Plant Proteins; D011422:Propionates; D011994:Recombinant Proteins; D008031:Lignin; D000217:Acyltransferases; C495469:p-coumaric acid