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Glucan, water dikinase activity stimulates breakdown of starch granules by plastidial β-amylases
Citation
Edner, C and Li, J and Albrecht, T and Mahlow, S and Hejazi, M and Hussain, H and Kaplan, F and Guy, C and Smith, SM and Steup, M and Ritte, G, Glucan, water dikinase activity stimulates breakdown of starch granules by plastidial β-amylases, Plant Physiology, 145, (1) pp. 17-28. ISSN 0032-0889 (2007) [Refereed Article]
Copyright Statement
Copyright 2007 American Society of Plant Biologists
DOI: doi:10.1104/pp.107.104224
Abstract
Glucan phosphorylating enzymes are required for normal mobilization of starch in leaves of Arabidopsis (Arabidopsis thaliana) and potato (Solanum tuberosum), but mechanisms underlying this dependency are unknown. Using two different activity assays, we aimed to identify starch
degrading enzymes from Arabidopsis, whose activity is affected by glucan phosphorylation. Breakdown of granular starch by
a protein fraction purified from leaf extracts increased approximately 2-fold if the granules were simultaneously phosphorylated
by recombinant potato glucan, water dikinase (GWD). Using matrix-assisted laser-desorption ionization mass spectrometry several
putative starch-related enzymes were identified in this fraction, among them β-AMYLASE1 (BAM1; At3g23920) and ISOAMYLASE3 (ISA3; At4g09020). Experiments using purified recombinant enzymes showed that
BAM1 activity with granules similarly increased under conditions of simultaneous starch phosphorylation. Purified recombinant
potato ISA3 (StISA3) did not attack the granular starch significantly with or without glucan phosphorylation. However, starch
breakdown by a mixture of BAM1 and StISA3 was 2 times higher than that by BAM1 alone and was further enhanced in the presence
of GWD and ATP. Similar to BAM1, maltose release from granular starch by purified recombinant BAM3 (At4g17090), another plastid-localized
β-amylase isoform, increased 2- to 3-fold if the granules were simultaneously phosphorylated by GWD. BAM activity in turn strongly
stimulated the GWD-catalyzed phosphorylation. The interdependence between the activities of GWD and BAMs offers an explanation
for the severe starch excess phenotype of GWD-deficient mutants.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | glucan, water dikinase, beta-amylase, arabidopsis thaliana, starch, |
| Research Division: | Biological Sciences |
| Research Group: | Plant Biology |
| Research Field: | Plant Physiology |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding Knowledge |
| Objective Field: | Expanding Knowledge in the Biological Sciences |
| UTAS Author: | Smith, SM (Professor Steven Smith) |
| ID Code: | 101506 |
| Year Published: | 2007 |
| Web of Science® Times Cited: | 116 |
| Deposited By: | Plant Science |
| Deposited On: | 2015-06-25 |
| Last Modified: | 2015-09-24 |
| Downloads: | 0 |
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