Physiological Roles of the <i>β</i>-Substituted Alanine Synthase Gene Family in Arabidopsis

Watanabe, Mutsumi; Kusano, Miyako; Oikawa, Akira; Fukushima, Atsushi; Noji, Masaaki; Saito, Kazuki

doi:10.1104/pp.107.106831

Cited by 160 publications

(184 citation statements)

References 66 publications

Supporting

Mentioning

165

Contrasting

Unclassified

Order By: Relevance

“…The final solution (20 mL) was used to quantify the contents of 5OP, Glu, and Gln by cation analysis using CE-MS. The CE-MS system and conditions were as described by Watanabe et al (2008). Quantifications were performed using calibration curves of each compound.…”

Section: Ce-ms Analysesmentioning

confidence: 99%

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

et al. 2008

Self Cite

View full text Add to dashboard Cite

The degradation pathway of glutathione (GSH) in plants is not well understood. In mammals, GSH is predominantly metabolized through the g-glutamyl cycle, where GSH is degraded by the sequential reaction of g-glutamyl transpeptidase (GGT), g-glutamyl cyclotransferase, and 5-oxoprolinase to yield glutamate (Glu) and dipeptides that are subject to peptidase action. In this study, we examined if GSH is degraded through the same pathway in Arabidopsis (Arabidopsis thaliana) as occurs in mammals. In Arabidopsis, the oxoprolinase knockout mutants (oxp1-1 and oxp1-2) accumulate more 5-oxoproline (5OP) and less Glu than wild-type plants, suggesting substantial metabolite flux though 5OP and that 5OP is a major contributor to Glu steady-state levels. In the ggt1-1/ggt4-1/oxp1-1 triple mutant with no GGT activity in any organs except young siliques, the 5OP concentration in leaves was not different from that in oxp1-1, suggesting that GGTs are not major contributors to 5OP production in Arabidopsis. 5OP formation strongly tracked the level of GSH in Arabidopsis plants, suggesting that GSH is the precursor of 5OP in a GGT-independent reaction. Kinetics analysis suggests that g-glutamyl cyclotransferase is the major source of GSH degradation and 5OP formation in Arabidopsis. This discovery led us to propose a new pathway for GSH turnover in plants where GSH is converted to 5OP and then to Glu by the combined action of g-glutamyl cyclotransferase and 5-oxoprolinase in the cytoplasm.

show abstract

Section: Ce-ms Analysesmentioning

confidence: 99%

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

et al. 2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…Phylogenetic analysis shows that the b-cyanoalanine synthase in Arabidopsis is encoded by a small gene family of three members, CYS-C1 (At3g61440), CYS-D1 (At3g04940), and CYS-D2 (At5g28020) (Jost et al, 2000). The most abundant CAS enzyme is CYS-C1, which is localized in the mitochondria and contributes most of the CAS activity in root and leaf tissue (Watanabe et al, 2008). The isoforms CYS-D1 and CYS-D2 are localized in the cytosol and are much less abundant than CYS-C1 based on the numbers of ESTs as well as DNA microarray data and real-time PCR data (Watanabe et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Mitochondrial β-Cyanoalanine Synthase Is Essential for Root Hair Formation in Arabidopsis thaliana

et al. 2010

View full text Add to dashboard Cite

Cyanide is stoichiometrically produced as a coproduct of the ethylene biosynthesis pathway and is detoxified by b-cyanoalanine synthase enzymes. The molecular and phenotypical analysis of T-DNA insertion mutants of the mitochondrial b-cyanoalanine synthase CYS-C1 suggests that discrete accumulation of cyanide is not toxic for the plant and does not alter mitochondrial respiration rates but does act as a strong inhibitor of root hair development. The cys-c1 null allele is defective in root hair formation and accumulates cyanide in root tissues. The root hair defect is phenocopied in wild-type plants by the exogenous addition of cyanide to the growth medium and is reversed by the addition of hydroxocobalamin or by genetic complementation with the CYS-C1 gene. Hydroxocobalamin not only recovers the root phenotype of the mutant but also the formation of reactive oxygen species at the initial step of root hair tip growth. Transcriptional profiling of the cys-c1 mutant reveals that cyanide accumulation acts as a repressive signal for several genes encoding enzymes involved in cell wall rebuilding and the formation of the root hair tip as well as genes involved in ethylene signaling and metabolism. Our results demonstrate that mitochondrial b-cyanoalanine synthase activity is essential to maintain a low level of cyanide for proper root hair development.

show abstract

“…A combination of the metabolomic approach and these bioresources has been demonstrated to be a smart strategy to uncover the role of a functionally unknown gene. Using GC-MS and CE-MS, Watanabe et al [102] obtained a metabolome dataset of Arabidopsis seedlings of a wild-type plant, and several T-DNA insertion mutants having immature bsas (β-substituted alanine synthase) genes. Statistical analyses revealed that one unknown metabolite was not accumulated in one of the bsas mutants, namely, bsas3;1, whereas this unknown metabolite was detectable in sufficient quantities in the wild-type and other mutants.…”

Section: Future Prospectsmentioning

confidence: 99%

Rice Metabolomics

Oikawa

Mizutani

Kusano

et al. 2008

Rice

Self Cite

View full text Add to dashboard Cite

Metabolomics is a recently developed technology for comprehensive analysis of metabolites in organisms. Plant metabolites that are produced for the growth, development, and chemical defense of plants against climatic alterations or natural predators are also useful to us as nutrients or medicines; hence, it is important to comprehend the amounts and varieties of plant metabolites. Besides providing an understanding of the metabolic state in plants under various circumstances, metabolomic techniques are applicable to the clarification of the functions of unknown genes by using natural variants or mutants of the target plants. Furthermore, a metabolomic approach might be useful in the breeding of crops, since valuable plant traits such as taste and yield are closely related to metabolic conditions. Here, we describe the methodology of metabolomics including sample extraction and preparation, metabolite detection, and data processing and analysis, and introduce the application of metabolomic studies to rice.

show abstract

Physiological Roles of the β-Substituted Alanine Synthase Gene Family in Arabidopsis

Cited by 160 publications

References 66 publications

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

Mitochondrial β-Cyanoalanine Synthase Is Essential for Root Hair Formation in Arabidopsis thaliana

Rice Metabolomics

Contact Info

Product

Resources

About