Title
Synthesis, processing and export of cytoplasmic endo-ß-1,4-xylanase from barley aleurone during germination
Author
Caspers, M.P.M.
Lok, F.
Sinjorgo, K.M.C.
van Zeijl, M.
Nielsen, K.A.
Cameron-Mills, V.
Centraal Instituut voor Voedingsonderzoek TNO
Publication year
2001
Abstract
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.-
Subject
Nutrition
Amino Acid Sequence
Apoptosis
Blotting, Western
Cysteine Endopeptidases
Cytoplasm
Endo-1,4-beta Xylanases
Gene Expression Regulation, Plant
Genes, Plant
Germination
Green Fluorescent Proteins
Hordeum
Hydrolases
Indicators and Reagents
Luminescent Proteins
Microscopy, Confocal
Molecular Sequence Data
Molecular Weight
Plant Proteins
Protoplasts
RNA Precursors
Seeds
Starch
Xylosidases
Hordeum vulgare subsp. vulgare
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DOI
https://doi.org/10.1046/j.0960-7412.2001.01019.x
TNO identifier
72511
ISSN
0960-7412
Source
The Plant Journal, 26 (2), 191-204
Document type
article