title: Putative cationic cell-wall-bound peroxidase homologues in Arabidopsis, AtPrx2, AtPrx25, and AtPrx71, are involved in lignification.
abstract: The final step of lignin biosynthesis, which is catalyzed by a plant peroxidase, is the oxidative coupling of the monolignols to growing lignin polymers. Cationic cell-wall-bound peroxidase (CWPO-C) from poplar callus is a unique enzyme that has oxidative activity for both monolignols and synthetic lignin polymers. This study shows that putative CWPO-C homologues in Arabidopsis , AtPrx2, AtPrx25, and AtPrx71, are involved in lignin biosynthesis. Analysis of stem tissue using the acetyl bromide method and derivatization followed by the reductive cleavage method revealed a significant decrease in the total lignin content of ATPRX2 and ATPRX25 deficient mutants and altered lignin structures in ATPRX2, ATPRX25, and ATPRX71 deficient mutants. Among Arabidopsis peroxidases, AtPrx2 and AtPrx25 conserve a tyrosine residue on the protein surface, and this tyrosine may act as a substrate oxidation site as in the case of CWPO-C. AtPrx71 has the highest amino acid identity with CWPO-C. The results suggest a role for CWPO-C and CWPO-C-like peroxidases in the lignification of vascular plant cell walls.
authors.affiliation: Department of Forest and Forest Products Sciences, Kyushu University , 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581 Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Shigeto
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kiyonaga
authors.forename: Koki
authors.initials: K
authors.lastname: Fujita
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Kondo
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tsutsumi
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002412:Cations; D002473:Cell Wall / Q000201:enzymology*; D007527:Isoenzymes / Q000378:metabolism; D008031:Lignin / Q000096:biosynthesis*; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000737:chemistry
chemical_list: D029681:Arabidopsis Proteins; D002412:Cations; D007527:Isoenzymes; D014443:Tyrosine; D008031:Lignin; D010544:Peroxidases; C000597915:Prx2 protein, Arabidopsis; C000597914:Prx25 protein, Arabidopsis; C000597916:Prx71 protein, Arabidopsis