Synthesis, processing and export of cytoplasmic endo-ß-1,4-xylanase from barley aleurone during germination
article
We have identified the major endo-β-l,4-xylanase (XYN-1) in the aleurone of germinating barley grain, and show that it is expressed as a precursor of Mr 61 500 with both N- and C-terminal propeptides. XYN-1 is synthesized as an inactive enzyme in the cytoplasm, and only becomes active at a late stage of germination when the aleurone ceases to secrete hydrolases. A series of processing steps, mediated in part by aleurone cysteine endoproteases, yields a mature active enzyme of Mr 34 000. Processing and extracellular release of the mature enzyme coincide with the programmed cell death (PCD)-regulated disintegration of aleurone cells. We discuss the significance of delayed aleurone cell-wall degradation by endoxylanases in relation to the secretory capacity of the aleurone, and propose a novel role for aleurone PCD in facilitating the export of hydrolases. Chemicals/CAS: alpha-Amylase, EC 3.2.1.1; Cysteine Endopeptidases, EC 3.4.22.-; Endo-1,4-beta Xylanases, EC 3.2.1.8; Green Fluorescent Proteins, 147336-22-9; Hydrolases, EC 3.-; Indicators and Reagents; Luminescent Proteins; Plant Proteins; RNA Precursors; Starch, 9005-25-8; Xylosidases, EC 3.2.1.-
Topics
Amino Acid SequenceApoptosisBlotting, WesternCysteine EndopeptidasesCytoplasmEndo-1,4-beta XylanasesGene Expression Regulation, PlantGenes, PlantGerminationGreen Fluorescent ProteinsHordeumHydrolasesIndicators and ReagentsLuminescent ProteinsMicroscopy, ConfocalMolecular Sequence DataMolecular WeightPlant ProteinsProtoplastsRNA PrecursorsSeedsStarchXylosidasesHordeum vulgare subsp. vulgare
TNO Identifier
72511
ISSN
09607412
Source
The Plant Journal, 26(2), pp. 191-204.
Pages
191-204
Files
To receive the publication files, please send an e-mail request to TNO Repository.