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A Medicago truncatula homoglutathione synthetase is derived from glutathione synthetase by gene duplication.
- Source :
- Plant Physiology; August 2001, Vol. 126 Issue: 4 p1706-1715, 10p
- Publication Year :
- 2001
-
Abstract
- Glutathione (GSH) and homo-GSH (hGSH) are the major low-molecular weight thiols synthesized in Medicago truncatula. Two M. truncatula cDNAs (gshs1 and gshs2) corresponding to a putative GSH synthetase (GSHS) and a putative hGSH synthetase (hGSHS) were characterized. Heterologous expression of gshs1 and gshs2 cDNAs in an Escherichia coli strain deficient in GSHS activity showed that GSHS1 and GSHS2 are a GSHS and an hGSHS, respectively. Leucine-534 and proline-535 present in hGSHS were substituted by alanines that are conserved in plant GSHS. These substitutions resulted in a strongly stimulated GSH accumulation in the transformed E. coli strain showing that these residues play a crucial role in the differential recognition of beta-alanine and glycine by hGSHS. Phylogenetic analysis of GSHS2 and GSHS1 with other eukaryotic GSHS sequences indicated that gshs2 and gshs1 are the result of a gene duplication that occurred after the divergence between Fabales, Solanales, and Brassicales. Analysis of the structure of gshs1 and gshs2 genes shows they are both present in a cluster and in the same orientation in the M. truncatula genome, suggesting that the duplication of gshs1 and gshs2 occurred via a tandem duplication.
Details
- Language :
- English
- ISSN :
- 00320889 and 15322548
- Volume :
- 126
- Issue :
- 4
- Database :
- Supplemental Index
- Journal :
- Plant Physiology
- Publication Type :
- Periodical
- Accession number :
- ejs57115428
- Full Text :
- https://doi.org/10.1104/pp.126.4.1706