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α-amylase is not required for breakdown of transitory starch in Arabidopsis leaves
Citation
Yu, T-S and Zeeman, SC and Thorneycroft, D and Fulton, DC and Dunstan, H and Lue, W-L and Hegemann, B and Tung, S-Y and Umemoto, T and Chapple, A and Tsai, D-L and Wang, S-M and Smith, AM and Chen, J and Smith, SM, α-amylase is not required for breakdown of transitory starch in Arabidopsis leaves, Journal of Biological Chemistry, 280, (11) pp. 9773-9779. ISSN 0021-9258 (2005) [Refereed Article]
Copyright Statement
© 2005 by The American Society for Biochemistry and Molecular Biology
DOI: doi:10.1074/jbc.M413638200
Abstract
The Arabidopsis thaliana genome encodes three α-amylase-like proteins (AtAMY1, AtAMY2, and AtAMY3). Only AtAMY3 has a predicted N-terminal transit
peptide for plastidial localization. AtAMY3 is an unusually large α-amylase (93.5 kDa) with the C-terminal half showing similarity
to other known α-amylases. When expressed in Escherichia coli, both the whole AtAMY3 protein and the C-terminal half alone show α-amylase activity. We show that AtAMY3 is localized in
chloroplasts. The starch-excess mutant of Arabidopsis sex4, previously shown to have reduced plastidial α-amylase activity, is deficient in AtAMY3 protein. Unexpectedly, T-DNA knock-out
mutants of AtAMY3 have the same diurnal pattern of transitory starch metabolism as the wild type. These results show that AtAMY3 is not required
for transitory starch breakdown and that the starch-excess phenotype of the sex4 mutant is not caused simply by deficiency of AtAMY3 protein. Knock-out mutants in the predicted non-plastidial α-amylases
AtAMY1 and AtAMY2 were also isolated, and these displayed normal starch breakdown in the dark as expected for extraplastidial
amylases. Furthermore, all three AtAMY double knock-out mutant combinations and the triple knock-out degraded their leaf starch
normally. We conclude that α-amylase is not necessary for transitory starch breakdown in Arabidopsis leaves.
Item Details
Item Type: | Refereed Article |
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Keywords: | arabidopsis thaliana, alpha-amylase proteins, starch breakdown |
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: | 101519 |
Year Published: | 2005 |
Web of Science® Times Cited: | 125 |
Deposited By: | Plant Science |
Deposited On: | 2015-06-25 |
Last Modified: | 2015-09-25 |
Downloads: | 0 |
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