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Two isoforms of glutamate decarboxylase in Arabidopsis are regulated by calcium/calmodulin and differ in organ distribution
Year:
1998
Source of publication :
Plant Molecular Biology
Authors :
Arazi, Tzahi
;
.
Volume :
37
Co-Authors:
Zik, M., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Arazi, T., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Snedden, W.A., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Botany, University of Toronto, Toronto, Ont., Canada
Fromm, H., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Facilitators :
From page:
967
To page:
975
(
Total pages:
9
)
Abstract:
The nucleotide sequences of cDNAs encoding two isoforms of Arabidopsis glutamate decarboxylase, designated GAD1 (57.1 kDa) and GAD2 (56.1 kDa) and sharing 82% identical amino acid sequences, were determined. The recombinant proteins bound [35S] calmodulin (CAM) in the presence of calcium, and a region of 30-32 amino acids from the C-terminal of each isoform was sufficient for CaM binding when fused to glutathione S-transferase. Full-length GAD1 and GAD2 were expressed in Sf9 insect cells infected with recombinant baculovirus vectors. Recombinant proteins were partially purified by CaM affinity chromatography and were found to exhibit glutamate decarboxylase activity, which was dependent on the presence of Ca2+/CaM at pH 7.3. Southern hybridizations with GAD gene-specific probes suggest that Arabidopsis possesses one gene related to GADI and one to GAD2. Northern hybridization and western blot analysis revealed that GAD1 was expressed only in roots and GAD2 in roots, leaves, inflorescence stems and flowers. Our study provides the first evidence for the occurrence of multiple functional Ca2+/CaM-regulated GAD gene products in a single plant, suggesting that regulation of Arabidopsis GAD activity involves modulation of isoform-specific gene expression and stimulation of the catalytic activity of GAD by calcium signalling via CaM.
Note:
Related Files :
arabidopsis
carboxy terminal sequence
Glutathione transferase
Sequence Homology, Amino Acid
Show More
Related Content
More details
DOI :
10.1023/A:1006047623263
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
21116
Last updated date:
02/03/2022 17:27
Creation date:
16/04/2018 23:41
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Scientific Publication
Two isoforms of glutamate decarboxylase in Arabidopsis are regulated by calcium/calmodulin and differ in organ distribution
37
Zik, M., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Arazi, T., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Snedden, W.A., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Botany, University of Toronto, Toronto, Ont., Canada
Fromm, H., Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
Two isoforms of glutamate decarboxylase in Arabidopsis are regulated by calcium/calmodulin and differ in organ distribution
The nucleotide sequences of cDNAs encoding two isoforms of Arabidopsis glutamate decarboxylase, designated GAD1 (57.1 kDa) and GAD2 (56.1 kDa) and sharing 82% identical amino acid sequences, were determined. The recombinant proteins bound [35S] calmodulin (CAM) in the presence of calcium, and a region of 30-32 amino acids from the C-terminal of each isoform was sufficient for CaM binding when fused to glutathione S-transferase. Full-length GAD1 and GAD2 were expressed in Sf9 insect cells infected with recombinant baculovirus vectors. Recombinant proteins were partially purified by CaM affinity chromatography and were found to exhibit glutamate decarboxylase activity, which was dependent on the presence of Ca2+/CaM at pH 7.3. Southern hybridizations with GAD gene-specific probes suggest that Arabidopsis possesses one gene related to GADI and one to GAD2. Northern hybridization and western blot analysis revealed that GAD1 was expressed only in roots and GAD2 in roots, leaves, inflorescence stems and flowers. Our study provides the first evidence for the occurrence of multiple functional Ca2+/CaM-regulated GAD gene products in a single plant, suggesting that regulation of Arabidopsis GAD activity involves modulation of isoform-specific gene expression and stimulation of the catalytic activity of GAD by calcium signalling via CaM.
Scientific Publication
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