Arabidopsis cyt1 mutants are deficient in a mannose-1-phosphate guanylyltransferase and point to a requirement of N-linked glycosylation for cellulose biosynthesis
| Autor: | Wolfgang Lukowitz, Todd C. Nickle, David W. Meinke, Robert L. Last, Patricia L. Conklin, Christopher R. Somerville |
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| Jazyk: | angličtina |
| Rok vydání: | 2001 |
| Předmět: |
Guanylyltransferase
Glycosylation Mutant Blotting Western Molecular Sequence Data Arabidopsis Polysaccharide Genes Plant Plant Roots Cell wall chemistry.chemical_compound Amino Acid Sequence Cloning Molecular Cellulose chemistry.chemical_classification Multidisciplinary biology Sequence Homology Amino Acid Callose Tunicamycin Biological Sciences biology.organism_classification Ascorbic acid Blotting Northern Nucleotidyltransferases chemistry Biochemistry Mutation |
| Popis: | Arabidopsis cyt1 mutants have a complex phenotype indicative of a severe defect in cell wall biogenesis. Mutant embryos arrest as wide, heart-shaped structures characterized by ectopic accumulation of callose and the occurrence of incomplete cell walls. Texture and thickness of the cell walls are irregular, and unesterified pectins show an abnormally diffuse distribution. To determine the molecular basis of these defects, we have cloned the CYT1 gene by a map-based approach and found that it encodes mannose-1-phosphate guanylyltransferase. A weak mutation in the same gene, called vtc1 , has previously been identified on the basis of ozone sensitivity due to reduced levels of ascorbic acid. Mutant cyt1 embryos are deficient in N-glycosylation and have an altered composition of cell wall polysaccharides. Most notably, they show a 5-fold decrease in cellulose content. Characteristic aspects of the cyt1 phenotype, including radial swelling and accumulation of callose, can be mimicked with the inhibitor of N-glycosylation, tunicamycin. Our results suggest that N-glycosylation is required for cellulose biosynthesis and that a deficiency in this process can account for most phenotypic features of cyt1 embryos. |
| Databáze: | OpenAIRE |
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