Cytosol-Localized UDP-Xylose Synthases Provide the Major Source of UDP-Xylose for the Biosynthesis of Xylan and Xyloglucan
| Autor: | Quincy Teng, Ruiqin Zhong, Youxi Yuan, Zheng-Hua Ye, Marziyeh Haghighat, Robert L. Dasher, Samuel T Furey |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0106 biological sciences
0301 basic medicine Physiology Carboxy-Lyases Mutant Arabidopsis Golgi Apparatus Plant Science 01 natural sciences Gene Expression Regulation Enzymologic Cell wall 03 medical and health sciences chemistry.chemical_compound Cytosol Biosynthesis Cell Wall Gene Expression Regulation Plant Xylem Arabidopsis thaliana Glucans Microscopy Confocal biology ATP synthase Plant Stems Chemistry Arabidopsis Proteins Reverse Transcriptase Polymerase Chain Reaction Gene Expression Profiling food and beverages Cell Biology General Medicine biology.organism_classification Plants Genetically Modified Xylan carbohydrates (lipids) Xyloglucan Isoenzymes 030104 developmental biology Uridine Diphosphate Xylose Biochemistry Multigene Family Spectrometry Mass Matrix-Assisted Laser Desorption-Ionization Mutation biology.protein RNA Interference Xylans 010606 plant biology & botany |
| Zdroj: | Plantcell physiology. 58(1) |
| ISSN: | 1471-9053 |
| Popis: | Xylan and xyloglucan are the two major cell wall hemicelluloses in plants, and their biosynthesis requires a steady supply of the sugar donor, UDP-xylose. UDP-xylose is synthesized through conversion of UDP-glucuronic acid (UDP-GlcA) by the activities of UDP-xylose synthase (UXS). There exist six UXS genes in the Arabidopsis thaliana genome; three of them (UXS1, UXS2 and UXS4) encode Golgi-localized enzymes and the other three (UXS3, UXS5 and UXS6) encode cytosol-localized enzymes. In this report, we investigated the contributions of these UXS genes in supplying UDP-xylose for the biosynthesis of xylan and xyloglucan. Expression analyses revealed that the six UXS genes exhibited distinct and overlapping expression patterns in different cell types of stems, root-hypocotyls and young seedlings, and that the relative enzymatic activity of UXS in the cytosol was 17 times higher than that in the Golgi. Among the six UXS genes, UXS3, UXS5 and UXS6 showed the highest expression in stems and were expressed predominantly in xylem cells and interfascicular fibers. Their predominant expression in secondary wall-forming cells was consistent with the finding that the expression of UXS3, UXS5 and UXS6 was directly activated by the secondary wall NAC master switches. Although simultaneous mutations of UXS1, UXS2 and UXS4 did not cause any apparent effects on plant growth and xylan biosynthesis, simultaneous down-regulation/mutations of UXS3, UXS5 and UXS6 led to a drastic reduction in secondary wall thickening, a severe deformation of xylem vessels, a significant decrease in xylan content without an apparent reduction in its chain length and an absence of GlcA side chains in xylan, which are reminiscent of the phenotypes of some known xylan-deficient mutants. Moreover, Immunolocalization with two xyloglucan monoclonal antibodies, LM15 and LM25, revealed a significant reduction in the amount of xylogulcan in the primary walls. These results demonstrate that the cytosol-localized UXS3, UXS5 and UXS6 play a predominant role in the supply of UDP-xylose for the biosynthesis of xylan and xyloglucan. |
| Databáze: | OpenAIRE |
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