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Molecular Plant 2013年第4期6卷 1373-1375页

作者： Guangyan Xiong Kun Cheng markus pauly Energy Biosciences Institute University of California Berkeley CA 94720 USA Department of Plant and Microbial Biology University of California Berkeley CA 94720 USA

Dear Editor, Plant cell walls consist of a complex composite of the poly- saccharides cellulose, various hemicelluloses, pectic polysaccharides, and the polyphenol lignin. Most cell wall polysaccharides are O-acetylated to varying extents, depending on plant spe- cies and tissue type （Gille and pauly, 2012）. However, the function of this substituent in planta remains enigmatic. Recently, several proteins have been identified that mediate polysac- charide O-acetylation in the plant model species Arabidopsis thaliana （Gille and pauly, 2012）. One protein, a member of the ＇trichome birefringence-like＇（TBL） protein family, AXY4/ TBL27, was proven to be required for the specific O-acetylation of the hemicellulose xyloglucan representing a potential xylo- glucan O-acetyltransferase （Gille et al., 2011）. Other TBL mem- bers （there are a total of 46 members in Arabidopsis; Bischoff et al., 2010） might thus be involved in contributing to the O-acetylation of the other wall polymers （Gille et al., 2011）.

关键词： O-Acetylation Enzymatic Recalcitrance Arabidopsis

Microanalysis of Plant Cell Wall Polysaccharides

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Molecular Plant 2009年第5期2卷 922-932页

作者： Nicolai Obel Veronika Erben Tatjana Schwarz Stefan Kuhnel Andrea Fodor markus pauly Max-Planck-lnstitut for Molecular Plant Physiology Am Muhlenberg 1 14476 Golm Potsdam Germany Present address: European Patent Office Erhardtstrasse 27 Munich Germany Helmhotz Center Munich Institute of Biological and Medical Imaging Ingolstaedter Landstrass. 1 85764 Neuherberg Germany ageningen University Department of Agrotechnology and Food Sciences Laboratory of Food Chemistry Bomenweg 2 6703 HD Wageningen The Netherlands DOE Plant Research Lab. Michigan State University East Lansing MI 48864 USA

Oligosaccharide Mass Profiling （OLIMP） allows a fast and sensitive assessment of cell wall polymer structure when coupled with Matrix Assisted Laser Desorption Ionisation Time Of Flight Mass Spectrometry （MALDI-TOF MS）. The short time required for sample preparation and analysis makes possible the study of a wide range of plant organs, revealing a high degree of heterogeneity in the substitution pattern of wall polymers such as the cross-linking glycan xyloglucan and the pectic polysaccharide homogalacturonan. The high sensitivity of MALDI-TOF allows the use of small amounts of samples, thus making it possible to investigate the wall structure of single cell types when material is collected by such methods as laser micro-dissection. As an example, the analysis of the xyloglucan structure in the leaf cell types outer epidermis layer, entire epidermis cell layer, palisade mesophyll cells, and vascular bundles were investigated. OLIMP is amenable to in situ wall analysis, where wall polymers are analyzed on unprepared plant tissue itself without first isolating cell walls. In addition, OLIMP enables analysis of wall polymers in Golgi-enriched fractions, the location of nascent matrix polysaccharide biosynthesis, enabling separation of the processes of wall biosynthesis versus post-deposition apoplastic metabolism. These new tools will make possible a semi-quantitative analysis of the cell wall at an unprecedented level.

关键词： Carbohydrate metabolism xyloglucan mass spectrometry cell expansion cell walls Arabidopsis laser microdissection.

RNA-Seq Analysis of Developing Nasturtium Seeds （Tropaeolum majus）： Identification and Characterization of an Additional Galactosyltransferase Involved in Xyloglucan Biosynthesis

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Molecular Plant 2012年第5期5卷 984-992页

作者： Jacob K. Jensen Alex Schultink Kenneth Keegstra Curtis G. Wilkerson markus pauly DOE Great Lakes Bioenergy Research Center Michigan State University East Lansing MI 48824 USA Department of Plant Biology Michigan State University East Lansing MI 48824 USA Department of Plant and Microbial Biology UC Berkeley Berkeley CA 94720 USA MSU-DOE Plant Research Laboratory Michigan State University East Lansing MI 48824 USA Energy Biosciences Institute University of California Berkeley 30 Calvin Hall MC 5230 Berkeley CA 94720 USA

A deep-sequencing approach was pursued utilizing 454 and Illumina sequencing methods to discover new genes involved in xyloglucan biosynthesis, cDNA sequences were generated from developing nasturtium （Tropaeolum majus） seeds, which produce large amounts of non-fucosylated xyloglucan as a seed storage polymer. In addition to known xyloglucan biosynthetic genes, a previously uncharacterized putative xyloglucan galactosyltransferase was iden- tified. Analysis of an Arabidopsis thaliana mutant line defective in the corresponding ortholog （AT5G62220） revealed that this gene shows no redundancy with the previously characterized xyloglucan galactosyltransferase, MUR3, but is required for galactosyl-substitution of xyloglucan at a different position. The gene was termed XLT2 for Xyloglucan L-side chain galactosylTransferase position 2. It represents an enzyme in the same subclade of glycosyltransferase family 47 as MUR3. A double mutant defective in both MUR3 （mur3.1） and XLT2 led to an Arabidopsis plant with xyloglucan that consists essentially of only xylosylated glucosyl units, with no further substitutions.

关键词： seed biology cell walls nasturtium storage polymers xyloglucan.

A Xyloglucan Backbone 6-O-Acetyltransferase from Brachypodium distachyon Modulates Xyloglucan Xylosylation

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Molecular Plant 2016年第4期9卷 615-617页

作者： Lifeng Liu Mon Mandy Hsia Murali Dama John Vogel markus pauly Department of Plant & Microbial Biology University of California Berkeley CA 94720 USA U.S. Department of Agriculture Western Regional Research Center Albany CA 94710 USA U.S. Department of Energy Joint Genome Institute Walnut Creek CA 94598 USA

Dear Editor,Plant cells are surrounded and protected by cell walls, which consist primarily of polymers such as cellulose, hemicelluloses, pectic polysaccharides, and the polyphenol lignin. One of the ma- jor hemicelluloses in the primary cell wall is xyloglucan （XyG）, which consists of a β-1,4-glucan backbone containing xylosyl substituents. XyG attaches and partially covers the surface of cellulose microfibrils and is therefore thought to act as a spacer between microfibrils, reducing cellulose aggregation （pauly et al., 2013）.

关键词： Plant cells surrounded

Arabidopsis thaliana AtUTr7 Encodes a Golgi-Localized UDP-Glucose/UDP-Galactose Transporter that Affects Lateral Root Emergence

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Molecular Plant 2012年第6期5卷 1263-1280页

作者： Michael Handford Cecilia Rodriguez-Furlan Lorena Marchan Marcelo Segura Daniela Gomez Elena Alvarez-Buyllal Guang-Yan Xiong markus pauly Ariel Orellana Department of Biology Faculty of Sciences University of Chile Santiago Chile Present address: Department of Biochemistry University of Cambridge Cambridge CB2 1QW UK Centro de Biotecnologia Vegetal Facultad de Ciencias Biologicas Universidad Andres Bello Republica 217 Santiago Chile Present address: Facultad de Ciencias Biologicas Universidad AndrOs Bello Vina del Mar Chile Present address: Department of Pathobiology School of Veterinary Medicine University of Pennsylvania Philadelphia PA USA Instituto de Ecologia UNAM Mexico City Mexico Department of Plant and Microbial Biology University of California Berkeley CA 94720 USA FONDAP Center for Genome Regulation

Nucleotide sugar transporters （NSTs） are antiporters comprising a gene family that plays a fundamental role in the biosynthesis of complex cell wall polysaccharides and glycoproteins in plants. However, due to the limited number of related mutants that have observable phenotypes, the biological function（s） of most NSTs in cell wall biosynthesis and assembly have remained elusive. Here, we report the characterization of AtUTr7 from Arabidopsis （Arabidopsis thaliana （L.） Heynh.）, which is homologous to multi-specific UDP-sugar transporters from Drosophila melanogaster, humans, and Caenorhabditis elegans. We show that AtUTr7 possesses the common structural characteristics conserved among NSTs. Using a green fluorescent protein （GFP） tagged version, we demonstrate that AtUTr7 is localized in the Golgi apparatus. We also show that AtUTr7 is widely expressed, especially in the roots and in specific floral organs. Additionally, the results of an in vitro nucleotide sugar transport assay carried out with a tobacco and a yeast expression system suggest that AtUTr7 is capable of transferring UDP-Gal and UDP-GIc, but not a range of other UDP- and GDP-sugars, into the Golgi lumen. Mutants lacking expression of AtUTr7 exhibited an early proliferation of lateral roots as well as distorted root hairs when cultivated at high sucrose concentrations. Furthermore, the distribution of homogalacturonan with a low degree of methyl esterification differed in lateral root tips of the mutant compared to wild-type plants, although additional analytical procedures revealed no further differences in the composition of the root cell walls. This evidence suggests that the transport of UDP-Gal and UDP-GIc into the Golgi under conditions of high root biomass production plays a role in lateral root and root hair development.

关键词： nucleotide sugars nucleotide sugar transporters Golgi apparatus cell wall.

Arabinosylation of a Yariv-Precipitable Cell Wall Polymer Impacts Plant Growth as Exemplified by the Arabidopsis Glycosyltransferase Mutant ray1

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Molecular Plant 2013年第4期6卷 1369-1372页

作者： Sascha Gille Vaishali Sharma Edward E.K. Baidoo Jay D. Keasling Henrik Vibe Scheller markus pauly Energy Biosciences Institute University of California Berkeley CA 94720 USA Joint BioEnergy Institute Emeryville CA 94608 USA Physical Biosciences Division Lawrence Berkeley National Laboratory Berkeley CA 94720 USA Department of Chemical and Biomolecular Engineering Department of Bioengineering University of California Berkeley CA 94720 USA Department of Plant and Microbial Biology University of California Berkeley CA 94720 USA

Dear Editor, Plant cells are encased by cell walls--rigid yet highly dynamic composite structures, which consist of cellulose, hemicelluloses, pectic polysaccharides, glycoproteins, and the polyphenol lignin （Somerville et al., 2004）. Biosynthesis of the wall polysaccharides is facilitated by donor- and acceptor- substrate-specific glycosyltransferases catalyzing the transfer of the sugar moiety from a nucleotide sugar to form a specific glycosidic linkage. Glycosyltransferases have been grouped into families based on primary structure, one of which is fam- ily GT77 （***/GT77_***）.

关键词： Yariv-Precipitable Exemplified Arabidopsis Glycosyltransferase

Pectin May Hinder the Unfolding of Xyloglucan Chains during Cell Deformation： Implications of the Mechanical Performance of Arabidopsis Hypocotyls with Pectin Alterations

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Molecular Plant 2009年第5期2卷 990-999页

作者： Willie Abasolo Michaela Eder Kazuchika Yamauchi Nicolai Obel Antje Reinecke Lutz Neumetzler John W.C. Dunlop Gregory Mouille markus pauly Herman Hofte Ingo Burgert Max-Planck-lnstitute of Colloids and Interfaces Department of Biomaterials Potsdam Germany College of Forestry and Natural Resources University of the Philippines Los Banos Philippines Department of Socio-Environmental Energy Science Kyoto University Japan Max-Planck-lnstitute for Molecular Plant Physiology Potsdam Germany Laboratoire de Biologie Cellulaire UR501 Institute Jean-Pierre Bourgin INRA Versailles France Michigan State University Plant Research Laboratory East Lansing Michigan USA

Plant cell walls, like a multitude of other biological materials, are natural fiber-reinforced composite materials. Their mechanical properties are highly dependent on the interplay of the stiff fibrous phase and the soft matrix phase and on the matrix deformation itself. Using specific Arabidopsis thaliana mutants, we studied the mechanical role of the matrix assembly in primary cell walls of hypocotyls with altered xyloglucan and pectin composition. Standard microtensile tests and cyclic loading protocols were performed on tour1 hypocotyls with affected RGII borate diester cross-links and a hindered xyloglucan fucosylation as well as qua2 exhibiting 50% less homogalacturonan in comparison to wild-type. As a control, wild-type plants （Col-0） and mur2 exhibiting a specific xyloglucan fucosylation and no differences in the pectin network were utilized. In the standard tensile tests, the ultimate stress levels （-tensile strength） of the hypocotyls of the mutants with pectin alterations （mur1, qua2） were rather unaffected, whereas their tensile stiffness was noticeably reduced in comparison to Col-0. The cyclic loading tests indicated a stiffening of all hypocotyls after the first cycle and a plastic deformation during the first straining, the degree of which, however, was much higher for tour1 and qua2 hypocotyls. Based on the mechanical data and current cell wall models, it is assumed that folded xyloglucan chains between cellulose fibrils may tend to unfold during straining of the hypocotyls. This response is probably hindered by geometrical constraints due to pectin rigidity.

关键词： Arabidopsis thaliana mutants cellulose xyloglucan pectin cyclic loading tests.