alexa Ascorbic acid in plants: biosynthesis and function.
Biochemistry

Biochemistry

Enzyme Engineering

Author(s): Smirnoff N, Wheeler GL

Abstract Share this page

Abstract Ascorbic acid (vitamin C) is an abundant component of plants. It reaches a concentration of over 20 mM in chloroplasts and occurs in all cell compartments, including the cell wall. It has proposed functions in photosynthesis as an enzyme cofactor (including synthesis of ethylene, gibberellins and anthocyanins) and in control of cell growth. A biosynthetic pathway via GDP-mannose, GDP-L-galactose, L-galactose, and L-galactono-1,4-lactone has been proposed only recently and is supported by molecular genetic evidence from the ascorbate-deficient vtc 1 mutant of Arabidopsis thaliana. Other pathways via uronic acids could provide minor sources of ascorbate. Ascorbate, at least in some species, is a precursor of tartrate and oxalate. It has a major role in photosynthesis, acting in the Mehler peroxidase reaction with ascorbate peroxidase to regulate the redox state of photosynthetic electron carriers and as a cofactor for violaxanthin de-epoxidase, an enzyme involved in xanthophyll cycle-mediated photoprotection. The hypersensitivity of some of the vtc mutants to ozone and UV-B radiation, the rapid response of ascorbate peroxidase expression to (photo)-oxidative stress, and the properties of transgenic plants with altered ascorbate peroxidase activity all support an important antioxidative role for ascorbate. In relation to cell growth, ascorbate is a cofactor for prolyl hydroxylase that posttranslationally hydroxylates proline residues in cell wall hydroxyproline-rich glycoproteins required for cell division and expansion. Additionally, high ascorbate oxidase activity in the cell wall is correlated with areas of rapid cell expansion. It remains to be determined if this is a causal relationship and, if so, what is the mechanism. Identification of the biosynthetic pathway now opens the way to manipulating ascorbate biosynthesis in plants, and, along with the vtc mutants, this should contribute to a deeper understanding of the proposed functions of this multifaceted molecule. This article was published in Crit Rev Biochem Mol Biol and referenced in Enzyme Engineering

Relevant Expert PPTs

Relevant Speaker PPTs

  • Bozena Futoma-Koloch
    C3 component deposition on Salmonella O48 cells characterized by sialylated lipopolysaccharide and different pattern of outer membrane proteins
    PPT Version | PDF Version
  • Ildiko Molnar
    The role of tissue-specific type 2 5’-deiodinase enzyme activities in Graves’ orbitopathy and systemic sclerosis: a new candidate in thyroid autoimmunity
    PDF Version
  • Sumru Savas
    No relationship between lipoprotein-associated phospholipase A2, proinflammatory cytokines, and neopterin   in Alzheimer's disease
    PPT Version | PDF Version
  • Bonamali Pal
    Metal-TiO2 nano-photocatalysts for detoxification of toxic pesticides, dyes, polyaromatics pollutants and bacteria under UV-sunlight irradiation
    PPT Version | PDF Version
  • Guocheng Du
    One-step biosynthesis of α-keto acids by the L-amino acid deaminase: Biocatalyst construction and process optimization
    PPT Version | PDF Version
  • Heidi Schalchli
    Natural products of Anthracophyllum discolor: Ligninolytic enzymes and antifungal volatile compounds
    PPT Version | PDF Version
  • Mapitsi S Thantsha
    In vitro antagonistic effects of Listeria adhesion protein (LAP)-expressing Lactobacillus casei against Listeria monocytogenes and Salmonella Typhimurium Copenhagen
    PPT Version | PDF Version
  • Tibor Tot
    Multiparameter characterization of breast carcinoma: subgross, microscopy, proteins, and genes
    PPT Version | PDF Version
  • Monray Edward Williams
    Molecular validation of putative antimicrobial peptides for improved Human Immunodeficiency Virus diagnostics via HIV protein p24
    PPT Version | PDF Version
  • Kuna Yellamma
    Kuna-Yellamma-Sri-Venkateswara-University-India-Evaluation-of-neuroprotective-effect-of-silk-protein
    PPT Version | PDF Version
  • Yosef Yarden
    Classically, the 3’untranslated region (3’UTR) is that region in eukaryotic protein-coding genes from the translation termination codon to the polyA signal. It is transcribed as an integral part of the mRNA encoded by the gene. However, there exists another kind of RNA, which consists of the 3’UTR alone, without all other elements in mRNA such as 5’UTR and coding region. The importance of independent 3’UTR RNA (referred as I3’UTR) was prompted by results of artificially introducing such RNA species into malignant mammalian cells. Since 1991, we found that the middle part of the 3’UTR of the human nuclear factor for interleukin-6 (NF-IL6) or C/EBP gene exerted tumor suppression effect in vivo. Our subsequent studies showed that transfection of C/EBP 3’UTR led to down-regulation of several genes favorable for malignancy and to up-regulation of some genes favorable for phenotypic reversion. Also, it was shown that the sequences near the termini of the C/EBP 3’UTR were important for its tumor suppression activity. Then, the C/EBP 3’UTR was found to directly inhibit the phosphorylation activity of protein kinase CPKC in SMMC-7721, a hepatocarcinoma cell line. Recently, an AU-rich region in the C/EBP 3’UTR was found also to be responsible for its tumor suppression. Recently we have also found evidence that the independent C/EBP 3’UTR RNA is actually exists in human tissues, such as fetal liver and heart, pregnant uterus, senescent fibroblasts etc. Through 1990’s to 2000’s, world scientists found several 3’UTR RNAs that functioned as artificial independent RNAs in cancer cells and resulted in tumor suppression. Interestingly, majority of genes for these RNAs have promoter-like structures in their 3’UTR regions, although the existence of their transcribed products as independent 3’UTR RNAs is still to be confirmed. Our studies indicate that the independent 3’UTR RNA is a novel non-coding RNA species whose function should be the regulation not of the expression of their original mRNA, but of some essential life activities of the cell as a whole.
    PPT Version | PDF Version
  • Shigeomi Horito
    Reconstruction of a transmembrane protein tetraspanin (CD9) into lipid bilayer by interaction of ganglioside GM3 and tetraspanin
    PPT Version | PDF Version
  • Maria A. Miteva
    In silico screening to discover inhibitors of protein-protein interactions targeting angiogenesis
    PPT Version | PDF Version
  • Konrad Sandhoff
    Lysosomal & extracellular degradation of GlcCer: Protein & lipid modifiers
    PPT Version | PDF Version
  • Devathri Nanayakkara
    Context specific role of deubiquitylase enzyme, USP9X in oral squamous cell carcinoma
    PPT Version | PDF Version

Recommended Conferences

  • 3rd International Conference on Genetic and Protein Engineering
    Nov 02-Nov 03, 2017 Las Vegas, USA

Relevant Topics

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

Agri, Food, Aqua and Veterinary Science Journals

Dr. Krish

agrifoodaquavet@omicsonline.com

1-702-714-7001 Extn: 9040

Clinical and Biochemistry Journals

Datta A

clinical_biochem@omicsonline.com

1-702-714-7001Extn: 9037

Business & Management Journals

Ronald

business@omicsonline.com

1-702-714-7001Extn: 9042

Chemical Engineering and Chemistry Journals

Gabriel Shaw

chemicaleng_chemistry@omicsonline.com

1-702-714-7001 Extn: 9040

Earth & Environmental Sciences

Katie Wilson

environmentalsci@omicsonline.com

1-702-714-7001Extn: 9042

Engineering Journals

James Franklin

engineering@omicsonline.com

1-702-714-7001Extn: 9042

General Science and Health care Journals

Andrea Jason

generalsci_healthcare@omicsonline.com

1-702-714-7001Extn: 9043

Genetics and Molecular Biology Journals

Anna Melissa

genetics_molbio@omicsonline.com

1-702-714-7001 Extn: 9006

Immunology & Microbiology Journals

David Gorantl

immuno_microbio@omicsonline.com

1-702-714-7001Extn: 9014

Informatics Journals

Stephanie Skinner

omics@omicsonline.com

1-702-714-7001Extn: 9039

Material Sciences Journals

Rachle Green

materialsci@omicsonline.com

1-702-714-7001Extn: 9039

Mathematics and Physics Journals

Jim Willison

mathematics_physics@omicsonline.com

1-702-714-7001 Extn: 9042

Medical Journals

Nimmi Anna

medical@omicsonline.com

1-702-714-7001 Extn: 9038

Neuroscience & Psychology Journals

Nathan T

neuro_psychology@omicsonline.com

1-702-714-7001Extn: 9041

Pharmaceutical Sciences Journals

John Behannon

pharma@omicsonline.com

1-702-714-7001Extn: 9007

Social & Political Science Journals

Steve Harry

social_politicalsci@omicsonline.com

1-702-714-7001 Extn: 9042

 
© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version