title: Role of UDP-Glucuronic Acid Decarboxylase in Xylan Biosynthesis in Arabidopsis.
abstract: UDP-xylose (UDP-Xyl) is the Xyl donor used in the synthesis of major plant cell-wall polysaccharides such as xylan (as a backbone-chain monosaccharide) and xyloglucan (as a branching monosaccharide). The biosynthesis of UDP-Xyl from UDP-glucuronic acid (UDP-GlcA) is irreversibly catalyzed by UDP-glucuronic acid decarboxylase (UXS). Until now, little has been known about the physiological roles of UXS in plants. Here, we report that AtUXS1, AtUXS2, and AtUXS4 are located in the Golgi apparatus whereas AtUXS3, AtUXS5, and AtUXS6 are located in the cytosol. Although all six single AtUXS T-DNA mutants and the uxs1 usx2 uxs4 triple mutant show no obvious phenotype, the uxs3 uxs5 uxs6 triple mutant has an irregular xylem phenotype. Monosaccharide analysis showed that Xyl levels decreased in uxs3 uxs5 uxs6 and linkage analysis confirmed that the xylan content in uxs3 xus5 uxs6 declined, indicating that UDP-Xyl from cytosol AtUXS participates in xylan synthesis. Gel-permeation chromatography showed that the molecular weight of non-cellulosic polysaccharides in the triple mutants, mainly composed of xylans, is lower than that in the wild type, suggesting an effect on the elongation of the xylan backbone. Upon saccharification treatment stems of the uxs3 uxs5 uxs6 triple mutants released monosaccharides with a higher efficiency than those of the wild type. Taken together, our results indicate that the cytosol UXS plays a more important role than the Golgi-localized UXS in xylan biosynthesis.
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Beiqing
authors.initials: B
authors.lastname: Kuang
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Xianhai
authors.initials: X
authors.lastname: Zhao
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Zhou
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Wei
authors.initials: W
authors.lastname: Zeng
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
authors.forename: Junli
authors.initials: J
authors.lastname: Ren
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Berit
authors.initials: B
authors.lastname: Ebert
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Cherie T
authors.initials: CT
authors.lastname: Beahan
authors.affiliation: Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Deng
authors.affiliation: Institute of Botany, The Chinese Academy of Science, Beijing 100093, China.
authors.forename: Qingyin
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
authors.forename: Gongke
authors.initials: G
authors.lastname: Zhou
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Monika S
authors.initials: MS
authors.lastname: Doblin
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia; Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Heazlewood
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Antony
authors.initials: A
authors.lastname: Bacic
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; Guangdong Province Research Center of woody forage engineering technology, Guangzhou, 510642, China. Electronic address: xychen@scau.edu.cn.
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Chen
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; Guangdong Province Research Center of woody forage engineering technology, Guangzhou, 510642, China. Electronic address: wuaimin@scau.edu.cn.
authors.forename: Ai-Min
authors.initials: AM
authors.lastname: Wu
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005936:Glucans / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D009154:Mutation; D014990:Xylans / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D005936:Glucans; D014990:Xylans; C029353:xyloglucan; D002262:Carboxy-Lyases; C023257:UDPglucuronate decarboxylase
keywords: UDP-Glucuronic acid decarboxylase; UDP-Xylose; localization; xylan