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Panahabadi R, Ahmadikhah A, Farrokhi N. Genetic dissection of monosaccharides contents in rice whole grain using genome-wide association study. THE PLANT GENOME 2023; 16:e20292. [PMID: 36691363 DOI: 10.1002/tpg2.20292] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 11/02/2022] [Indexed: 06/17/2023]
Abstract
The simplest form of carbohydrates are monosaccharides which are the building blocks for the synthesis of polymers or complex carbohydrates. Monosaccharide contents of 197 rice accessions were quantified by HPAEC-PAD in rice (Oryza sativa L.) whole grain (RWG). A genome-wide association study (GWAS) was carried out using 33,812 single nucleotide polymorphisms (SNPs) to identify corresponding genomic regions influencing neutral monosaccharides contents. In total, 49 GWAS signals contained in 17 genomic regions (quantitative trait loci [QTLs]) on seven chromosomes of rice were determined to be associated with monosaccharides contents of whole grain. The QTLs were found for fucose (1), mannose (1), xylose (2), arabinose (2), galactose (4), and rhamnose (7) contents, all of which are novel. Based on co-location of annotated rice genes in the vicinity of GWAS signals, the constituents of the whole grain were associated with the following candidate genes: arabinose content with α-N-arabinofuranosidase, pectinesterase inhibitor, and glucosamine-fructose-6-phosphate aminotransferase 1; xylose content with ZOS1-10 (a C2H2 zinc finger transcription factor [TF]); mannose content with aldose 1-epimerase-like protein and a MYB family TF; galactose content with a GT8 family member (galacturonosyltransferase-like 3), a GRAS family TF, and a GH16 family member (xyloglucan endotransglucosylase/hydrolase xyloglucan 23); fucose content with gibberellin 20 oxidase and a lysine-rich arabinogalactan protein 19, and finally rhamnose content with myo-inositol-1-phosphate synthase, UDP-arabinopyranose mutase, and COBRA-like protein precursor. The results of this study should improve our understanding of the genetic basis of the factors that might be involved in the biosynthesis, regulation, and turnover of monosaccharides in RWG, aiming to enhance the nutritional value of rice grain and impact the related industries.
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Affiliation(s)
- Rahele Panahabadi
- Faculty of Life Sciences and Biotechnology, Shahid Beheshti Univ., Tehran, Iran
| | | | - Naser Farrokhi
- Faculty of Life Sciences and Biotechnology, Shahid Beheshti Univ., Tehran, Iran
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2
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Simons ME, Narindoshvili T, Raushel FM. Biosynthesis of UDP-β-l-Arabinofuranoside for the Capsular Polysaccharides of Campylobacter jejuni. Biochemistry 2023; 62:3012-3019. [PMID: 37737649 PMCID: PMC10615251 DOI: 10.1021/acs.biochem.3c00298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/05/2023] [Indexed: 09/23/2023]
Abstract
Campylobacter jejuni is the leading cause of food poisoning in North America and Europe. The exterior surface of this bacterium is coated with a capsular polysaccharide (CPS) which enables adherence to the host epithelial cells and evasion of the host immune system. Many strains of C. jejuni can be differentiated from one another by changes in the sequence of the carbohydrates found within the CPS. The CPS structures of serotypes HS:15 and HS:41 of C. jejuni were chemically characterized and found to contain an l-arabinofuranoside moiety in the repeating CPS sequence. Sequence similarity and genome neighborhood networks were used to identify the putative gene cluster within the HS:15 serotype for the biosynthesis of the l-arabinofuranoside fragment. The first enzyme (HS:15.18) in the pathway was found to catalyze the NAD+-dependent oxidation of UDP-α-d-glucose to UDP-α-d-glucuronate, while the second enzyme (HS:15.19) catalyzes the NAD+-dependent decarboxylation of this product to form UDP-α-d-xylose. The UDP-α-d-xylose is then epimerized at C4 by the third enzyme (HS:15.17) to produce UDP-β-l-arabinopyranoside. In the last step, HS:15.16 catalyzes the FADH2-dependent conversion of UDP-β-l-arabinopyranoside into UDP-β-l-arabinofuranoside. The UDP-β-l-arabinopyranoside mutase catalyzed reaction was further interrogated by measurement of a positional isotope exchange reaction within [18O]-UDP-β-l-arabinopyranoside.
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Affiliation(s)
- Max Errickson Simons
- Department
of Biochemistry & Biophysics, Texas
A&M University, College
Station, Texas 77842, United States
| | - Tamari Narindoshvili
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Frank M. Raushel
- Department
of Biochemistry & Biophysics, Texas
A&M University, College
Station, Texas 77842, United States
- Department
of Chemistry, Texas A&M University, College Station, Texas 77842, United States
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3
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Barolo L, Commault AS, Abbriano RM, Padula MP, Kim M, Kuzhiumparambil U, Ralph PJ, Pernice M. Unassembled cell wall proteins form aggregates in the extracellular space of Chlamydomonas reinhardtii strain UVM4. Appl Microbiol Biotechnol 2022; 106:4145-4156. [PMID: 35599258 PMCID: PMC9200674 DOI: 10.1007/s00253-022-11960-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/28/2022] [Accepted: 05/02/2022] [Indexed: 11/25/2022]
Abstract
Abstract
The green microalga Chlamydomonas reinhardtii is emerging as a promising cell biofactory for secreted recombinant protein (RP) production. In recent years, the generation of the broadly used cell wall–deficient mutant strain UVM4 has allowed for a drastic increase in secreted RP yields. However, purification of secreted RPs from the extracellular space of C. reinhardtii strain UVM4 is challenging. Previous studies suggest that secreted RPs are trapped in a matrix of cell wall protein aggregates populating the secretome of strain UVM4, making it difficult to isolate and purify the RPs. To better understand the nature and behaviour of these extracellular protein aggregates, we analysed and compared the extracellular proteome of the strain UVM4 to its cell-walled ancestor, C. reinhardtii strain 137c. When grown under the same conditions, strain UVM4 produced a unique extracellular proteomic profile, including a higher abundance of secreted cell wall glycoproteins. Further characterization of high molecular weight extracellular protein aggregates in strain UVM4 revealed that they are largely comprised of pherophorins, a specific class of cell wall glycoproteins. Our results offer important new insights into the extracellular space of strain UVM4, including strain-specific secreted cell wall proteins and the composition of the aggregates possibly related to impaired RP purification. The discovery of pherophorins as a major component of extracellular protein aggregates will inform future strategies to remove or prevent aggregate formation, enhance purification of secreted RPs, and improve yields of recombinant biopharmaceuticals in this emerging cell biofactory. Key points • Extracellular protein aggregates hinder purification of recombinant proteins in C. reinhardtii • Unassembled cell wall pherophorins are major components of extracellular protein aggregates • Known aggregate composition informs future strategies for recombinant protein purification Supplementary Information The online version contains supplementary material available at 10.1007/s00253-022-11960-9.
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Affiliation(s)
- Lorenzo Barolo
- Climate Change Cluster, University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW, 2007, Australia.
| | - Audrey S Commault
- Climate Change Cluster, University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW, 2007, Australia
| | - Raffaela M Abbriano
- Climate Change Cluster, University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW, 2007, Australia
| | - Matthew P Padula
- School of Life Sciences and Proteomics Core Facility, Faculty of Science, University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW, 2007, Australia
| | - Mikael Kim
- Climate Change Cluster, University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW, 2007, Australia
| | | | - Peter J Ralph
- Climate Change Cluster, University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW, 2007, Australia
| | - Mathieu Pernice
- Climate Change Cluster, University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW, 2007, Australia
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4
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Mariette A, Kang HS, Heazlewood JL, Persson S, Ebert B, Lampugnani ER. Not Just a Simple Sugar: Arabinose Metabolism and Function in Plants. PLANT & CELL PHYSIOLOGY 2021; 62:1791-1812. [PMID: 34129041 DOI: 10.1093/pcp/pcab087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/05/2021] [Accepted: 06/15/2021] [Indexed: 06/12/2023]
Abstract
Growth, development, structure as well as dynamic adaptations and remodeling processes in plants are largely controlled by properties of their cell walls. These intricate wall structures are mostly made up of different sugars connected through specific glycosidic linkages but also contain many glycosylated proteins. A key plant sugar that is present throughout the plantae, even before the divergence of the land plant lineage, but is not found in animals, is l-arabinose (l-Ara). Here, we summarize and discuss the processes and proteins involved in l-Ara de novo synthesis, l-Ara interconversion, and the assembly and recycling of l-Ara-containing cell wall polymers and proteins. We also discuss the biological function of l-Ara in a context-focused manner, mainly addressing cell wall-related functions that are conferred by the basic physical properties of arabinose-containing polymers/compounds. In this article we explore these processes with the goal of directing future research efforts to the many exciting yet unanswered questions in this research area.
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Affiliation(s)
- Alban Mariette
- School of BioSciences, University of Melbourne, Parkville, VIC 3170, Australia
- Max Planck Institute of Molecular Plant Physiology, Golm, Germany, Am Mühlenberg 1, Potsdam-Golm 14476, Germany
| | - Hee Sung Kang
- School of BioSciences, University of Melbourne, Parkville, VIC 3170, Australia
| | - Joshua L Heazlewood
- School of BioSciences, University of Melbourne, Parkville, VIC 3170, Australia
| | - Staffan Persson
- School of BioSciences, University of Melbourne, Parkville, VIC 3170, Australia
- Department of Plant and Environmental Sciences, Copenhagen Plant Science Center (CPSC), University of Copenhagen, Thorvaldsensvej 40, Frederiksberg 1871, Denmark
- Joint International Research Laboratory of Metabolic and Developmental Sciences, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Berit Ebert
- School of BioSciences, University of Melbourne, Parkville, VIC 3170, Australia
| | - Edwin R Lampugnani
- School of BioSciences, University of Melbourne, Parkville, VIC 3170, Australia
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5
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Saqib A, Scheller HV, Fredslund F, Welner DH. Molecular characteristics of plant UDP-arabinopyranose mutases. Glycobiology 2020; 29:839-846. [PMID: 31679023 PMCID: PMC6861824 DOI: 10.1093/glycob/cwz067] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 08/22/2019] [Accepted: 08/22/2019] [Indexed: 12/13/2022] Open
Abstract
l-arabinofuranose is a ubiquitous component of the cell wall and various natural products in plants, where it is synthesized from cytosolic UDP-arabinopyranose (UDP-Arap). The biosynthetic machinery long remained enigmatic in terms of responsible enzymes and subcellular localization. With the discovery of UDP-Arap mutase in plant cytosol, the demonstration of its role in cell-wall arabinose incorporation and the identification of UDP-arabinofuranose transporters in the Golgi membrane, it is clear that the cytosolic UDP-Arap mutases are the key enzymes converting UDP-Arap to UDP-arabinofuranose for cell wall and natural product biosynthesis. This has recently been confirmed by several genotype/phenotype studies. In contrast to the solid evidence pertaining to UDP-Arap mutase function in vivo, the molecular features, including enzymatic mechanism and oligomeric state, remain unknown. However, these enzymes belong to the small family of proteins originally identified as reversibly glycosylated polypeptides (RGPs), which has been studied for >20 years. Here, we review the UDP-Arap mutase and RGP literature together, to summarize and systemize reported molecular characteristics and relations to other proteins.
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Affiliation(s)
- Anam Saqib
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, Kongens Lyngby, DK-2800, Denmark.,Industrial Enzymes and Biofuels Group, National Institute for Biotechnology and Genetic Engineering, Jhang Road, 44000 Faisalabad, Pakistan
| | - Henrik Vibe Scheller
- Feedstocks Division, Joint BioEnergy Institute, 5885 Hollis Street, Emeryville, CA 94608, USA; Environmental Engineering and Systems Biology Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA; Department of Plant & Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Folmer Fredslund
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, Kongens Lyngby, DK-2800, Denmark
| | - Ditte Hededam Welner
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, Kongens Lyngby, DK-2800, Denmark
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6
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Mathieu-Rivet E, Mati-Baouche N, Walet-Balieu ML, Lerouge P, Bardor M. N- and O-Glycosylation Pathways in the Microalgae Polyphyletic Group. FRONTIERS IN PLANT SCIENCE 2020; 11:609993. [PMID: 33391324 PMCID: PMC7773692 DOI: 10.3389/fpls.2020.609993] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/23/2020] [Indexed: 05/15/2023]
Abstract
The term microalga refers to various unicellular and photosynthetic organisms representing a polyphyletic group. It gathers numerous species, which can be found in cyanobacteria (i.e., Arthrospira) as well as in distinct eukaryotic groups, such as Chlorophytes (i.e., Chlamydomonas or Chlorella) and Heterokonts (i.e., diatoms). This phylogenetic diversity results in an extraordinary variety of metabolic pathways, offering large possibilities for the production of natural compounds like pigments or lipids that can explain the ever-growing interest of industrials for these organisms since the middle of the last century. More recently, several species have received particular attention as biofactories for the production of recombinant proteins. Indeed, microalgae are easy to grow, safe and cheap making them attractive alternatives as heterologous expression systems. In this last scope of applications, the glycosylation capacity of these organisms must be considered as this post-translational modification of proteins impacts their structural and biological features. Although these mechanisms are well known in various Eukaryotes like mammals, plants or insects, only a few studies have been undertaken for the investigation of the protein glycosylation in microalgae. Recently, significant progresses have been made especially regarding protein N-glycosylation, while O-glycosylation remain poorly known. This review aims at summarizing the recent data in order to assess the state-of-the art knowledge in glycosylation processing in microalgae.
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Affiliation(s)
| | | | | | - Patrice Lerouge
- UNIROUEN, Laboratoire Glyco-MEV EA4358, Normandie Université, Rouen, France
| | - Muriel Bardor
- UNIROUEN, Laboratoire Glyco-MEV EA4358, Normandie Université, Rouen, France
- Unité de Glycobiologie Structurale et Fonctionnelle (UGSF), UMR 8576, CNRS, Université de Lille, Lille, France
- *Correspondence: Muriel Bardor,
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7
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Mathieu-Rivet E, Lerouge P, Bardor M. Chlamydomonas reinhardtii: Protein Glycosylation and Production of Biopharmaceuticals. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/978-3-319-66360-9_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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8
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Welner DH, Tsai AYL, DeGiovanni AM, Scheller HV, Adams PD. X-ray diffraction analysis and in vitro characterization of the UAM2 protein from Oryza sativa. Acta Crystallogr F Struct Biol Commun 2017; 73:241-245. [PMID: 28368284 PMCID: PMC5379175 DOI: 10.1107/s2053230x17004587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 03/22/2017] [Indexed: 11/20/2022] Open
Abstract
The role of seemingly non-enzymatic proteins in complexes interconverting UDP-arabinopyranose and UDP-arabinofuranose (UDP-arabinosemutases; UAMs) in the plant cytosol remains unknown. To shed light on their function, crystallographic and functional studies of the seemingly non-enzymatic UAM2 protein from Oryza sativa (OsUAM2) were undertaken. Here, X-ray diffraction data are reported, as well as analysis of the oligomeric state in the crystal and in solution. OsUAM2 crystallizes readily but forms highly radiation-sensitive crystals with limited diffraction power, requiring careful low-dose vector data acquisition. Using size-exclusion chromatography, it is shown that the protein is monomeric in solution. Finally, limited proteolysis was employed to demonstrate DTT-enhanced proteolytic digestion, indicating the existence of at least one intramolecular disulfide bridge or, alternatively, a requirement for a structural metal ion.
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Affiliation(s)
- Ditte Hededam Welner
- DTU Bioengineering, Technical University of Denmark, Elektrovej, Building 375, 2800 Lyngby, Denmark
- Joint BioEnergy Institute, Emeryville, CA 94608, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Alex Yi-Lin Tsai
- Joint BioEnergy Institute, Emeryville, CA 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Andy M. DeGiovanni
- Joint BioEnergy Institute, Emeryville, CA 94608, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
| | - Henrik Vibe Scheller
- Joint BioEnergy Institute, Emeryville, CA 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Paul D. Adams
- Joint BioEnergy Institute, Emeryville, CA 94608, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA
- Department of Bioengineering, University of California Berkeley, Berkeley, CA 94720, USA
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9
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Kuttiyatveetil JRA, Sanders DAR. Analysis of plant UDP-arabinopyranose mutase (UAM): Role of divalent metals and structure prediction. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:510-519. [PMID: 28192204 DOI: 10.1016/j.bbapap.2017.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 01/16/2017] [Accepted: 02/03/2017] [Indexed: 11/16/2022]
Abstract
UDP-arabinopyranose mutase (UAM) is a plant enzyme which interconverts UDP-arabinopyranose (UDP-Arap; a six-membered sugar) to UDP-arabinofuranose (UDP-Araf; a five-membered sugar). Plant mutases belong to a small gene family called Reversibly Glycosylated Proteins (RGPs). So far, UAM has been identified in Oryza sativa (Rice), Arabidopsis thaliana and Hordeum vulgare (Barley). The enzyme requires divalent metal ions for catalytic activity. Here, the divalent metal ion dependency of UAMs from O. sativa (rice) and A. thaliana have been studied using HPLC-based kinetic assays. It was determined that UAM from these species had the highest relative activity in a range of 40-80μM Mn2+. Excess Mn2+ ion concentration decreased the enzyme activity. This trend was observed when other divalent metal ions were used to test activity. To gain a perspective of the role played by the metal ion in activity, an ab initio structural model was generated based on the UAM amino acid sequence and a potential metal binding region was identified. Based on our results, we propose that the probable role of the metal in UAM is stabilizing the diphosphate of the substrate, UDP-Arap.
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Affiliation(s)
- Jijin R A Kuttiyatveetil
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, S7N 5C9, Canada
| | - David A R Sanders
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, S7N 5C9, Canada.
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Kotake T, Yamanashi Y, Imaizumi C, Tsumuraya Y. Metabolism of L-arabinose in plants. JOURNAL OF PLANT RESEARCH 2016; 129:781-792. [PMID: 27220955 PMCID: PMC5897480 DOI: 10.1007/s10265-016-0834-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 03/31/2016] [Indexed: 05/07/2023]
Abstract
L-Arabinose (L-Ara) is a plant-specific sugar accounting for 5-10 % of cell wall saccharides in Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa). L-Ara occurs in pectic arabinan, rhamnogalacturonan II, arabinoxylan, arabinogalactan-protein (AGP), and extensin in the cell walls, as well as in glycosylated signaling peptides like CLAVATA3 and small glycoconjugates such as quercetin 3-O-arabinoside. This review focuses on recent advances towards understanding the generation of L-Ara and the metabolism of L-Ara-containing molecules in plants.
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Affiliation(s)
- Toshihisa Kotake
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama, 338-8570, Japan.
| | - Yukiko Yamanashi
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Chiemi Imaizumi
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Yoichi Tsumuraya
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama, 338-8570, Japan
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Willis JD, Smith JA, Mazarei M, Zhang JY, Turner GB, Decker SR, Sykes RW, Poovaiah CR, Baxter HL, Mann DGJ, Davis MF, Udvardi MK, Peña MJ, Backe J, Bar-Peled M, Stewart CN. Downregulation of a UDP-Arabinomutase Gene in Switchgrass ( Panicum virgatum L.) Results in Increased Cell Wall Lignin While Reducing Arabinose-Glycans. FRONTIERS IN PLANT SCIENCE 2016; 7:1580. [PMID: 27833622 PMCID: PMC5081414 DOI: 10.3389/fpls.2016.01580] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 10/06/2016] [Indexed: 05/09/2023]
Abstract
Background: Switchgrass (Panicum virgatum L.) is a C4 perennial prairie grass and a dedicated feedstock for lignocellulosic biofuels. Saccharification and biofuel yields are inhibited by the plant cell wall's natural recalcitrance against enzymatic degradation. Plant hemicellulose polysaccharides such as arabinoxylans structurally support and cross-link other cell wall polymers. Grasses predominately have Type II cell walls that are abundant in arabinoxylan, which comprise nearly 25% of aboveground biomass. A primary component of arabinoxylan synthesis is uridine diphosphate (UDP) linked to arabinofuranose (Araf). A family of UDP-arabinopyranose mutase (UAM)/reversible glycosylated polypeptides catalyze the interconversion between UDP-arabinopyranose (UDP-Arap) and UDP-Araf. Results: The expression of a switchgrass arabinoxylan biosynthesis pathway gene, PvUAM1, was decreased via RNAi to investigate its role in cell wall recalcitrance in the feedstock. PvUAM1 encodes a switchgrass homolog of UDP-arabinose mutase, which converts UDP-Arap to UDP-Araf. Southern blot analysis revealed each transgenic line contained between one to at least seven T-DNA insertions, resulting in some cases, a 95% reduction of native PvUAM1 transcript in stem internodes. Transgenic plants had increased pigmentation in vascular tissues at nodes, but were otherwise similar in morphology to the non-transgenic control. Cell wall-associated arabinose was decreased in leaves and stems by over 50%, but there was an increase in cellulose. In addition, there was a commensurate change in arabinose side chain extension. Cell wall lignin composition was altered with a concurrent increase in lignin content and transcript abundance of lignin biosynthetic genes in mature tillers. Enzymatic saccharification efficiency was unchanged in the transgenic plants relative to the control. Conclusion: Plants with attenuated PvUAM1 transcript had increased cellulose and lignin in cell walls. A decrease in cell wall-associated arabinose was expected, which was likely caused by fewer Araf residues in the arabinoxylan. The decrease in arabinoxylan may cause a compensation response to maintain cell wall integrity by increasing cellulose and lignin biosynthesis. In cases in which increased lignin is desired, e.g., feedstocks for carbon fiber production, downregulated UAM1 coupled with altered expression of other arabinoxylan biosynthesis genes might result in even higher production of lignin in biomass.
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Affiliation(s)
- Jonathan D. Willis
- Department of Plant Sciences, University of Tennessee, KnoxvilleTN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
| | - James A. Smith
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- Complex Carbohydrate Research Center, University of Georgia, AthensGA, USA
| | - Mitra Mazarei
- Department of Plant Sciences, University of Tennessee, KnoxvilleTN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
| | - Ji-Yi Zhang
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- The Samuel Roberts Noble Foundation, ArdmoreOK, USA
| | - Geoffrey B. Turner
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- The National Renewable Energy Laboratory, GoldenCO, USA
| | - Stephen R. Decker
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- The National Renewable Energy Laboratory, GoldenCO, USA
| | - Robert W. Sykes
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- The National Renewable Energy Laboratory, GoldenCO, USA
| | - Charleson R. Poovaiah
- Department of Plant Sciences, University of Tennessee, KnoxvilleTN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
| | - Holly L. Baxter
- Department of Plant Sciences, University of Tennessee, KnoxvilleTN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
| | - David G. J. Mann
- Department of Plant Sciences, University of Tennessee, KnoxvilleTN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
| | - Mark F. Davis
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- The National Renewable Energy Laboratory, GoldenCO, USA
| | - Michael K. Udvardi
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- The Samuel Roberts Noble Foundation, ArdmoreOK, USA
| | - Maria J. Peña
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- Complex Carbohydrate Research Center, University of Georgia, AthensGA, USA
| | - Jason Backe
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- Complex Carbohydrate Research Center, University of Georgia, AthensGA, USA
| | - Maor Bar-Peled
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- Complex Carbohydrate Research Center, University of Georgia, AthensGA, USA
- Plant Biology, University of Georgia, AthensGA, USA
- *Correspondence: Maor Bar-Peled, C. N. Stewart Jr.,
| | - C. N. Stewart
- Department of Plant Sciences, University of Tennessee, KnoxvilleTN, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak RidgeTN, USA
- *Correspondence: Maor Bar-Peled, C. N. Stewart Jr.,
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