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Common Bean (Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide
The common bean (Phaseolus vulgaris) constitutes an excellent source of vegetable dietary protein. However, there are sub-optimal levels of the essential amino acids, methionine and cysteine. On the other hand, P. vulgaris accumulates large amounts of the γ-glutamyl dipeptide of S-methylcysteine, an...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572574/ https://www.ncbi.nlm.nih.gov/pubmed/31091711 http://dx.doi.org/10.3390/plants8050126 |
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author | Saboori-Robat, Elham Joshi, Jaya Pajak, Aga Solouki, Mahmood Mohsenpour, Motahhareh Renaud, Justin Marsolais, Frédéric |
author_facet | Saboori-Robat, Elham Joshi, Jaya Pajak, Aga Solouki, Mahmood Mohsenpour, Motahhareh Renaud, Justin Marsolais, Frédéric |
author_sort | Saboori-Robat, Elham |
collection | PubMed |
description | The common bean (Phaseolus vulgaris) constitutes an excellent source of vegetable dietary protein. However, there are sub-optimal levels of the essential amino acids, methionine and cysteine. On the other hand, P. vulgaris accumulates large amounts of the γ-glutamyl dipeptide of S-methylcysteine, and lower levels of free S-methylcysteine and S-methylhomoglutathione. Past results suggest two distinct metabolite pools. Free S-methylcysteine levels are high at the beginning of seed development and decline at mid-maturation, while there is a biphasic accumulation of γ-glutamyl-S-methylcysteine, at early cotyledon and maturation stages. A possible model involves the formation of S-methylcysteine by cysteine synthase from O-acetylserine and methanethiol, whereas the majority of γ-glutamyl-S-methylcysteine may arise from S-methylhomoglutathione. Metabolite profiling during development and in genotypes differing in total S-methylcysteine accumulation showed that γ-glutamyl-S-methylcysteine accounts for most of the total S-methylcysteine in mature seed. Profiling of transcripts for candidate biosynthetic genes indicated that BSAS4;1 expression is correlated with both the developmental timing and levels of free S-methylcysteine accumulated, while homoglutathione synthetase (hGS) expression was correlated with the levels of γ-glutamyl-S-methylcysteine. Analysis of S-methylated phytochelatins by liquid chromatography and high resolution tandem mass spectrometry revealed only small amounts of homophytochelatin-2 with a single S-methylcysteine. The mitochondrial localization of phytochelatin synthase 2—predominant in seed, determined by confocal microscopy of a fusion with the yellow fluorescent protein—and its spatial separation from S-methylhomoglutathione may explain the lack of significant accumulation of S-methylated phytochelatins. |
format | Online Article Text |
id | pubmed-6572574 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-65725742019-06-18 Common Bean (Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide Saboori-Robat, Elham Joshi, Jaya Pajak, Aga Solouki, Mahmood Mohsenpour, Motahhareh Renaud, Justin Marsolais, Frédéric Plants (Basel) Article The common bean (Phaseolus vulgaris) constitutes an excellent source of vegetable dietary protein. However, there are sub-optimal levels of the essential amino acids, methionine and cysteine. On the other hand, P. vulgaris accumulates large amounts of the γ-glutamyl dipeptide of S-methylcysteine, and lower levels of free S-methylcysteine and S-methylhomoglutathione. Past results suggest two distinct metabolite pools. Free S-methylcysteine levels are high at the beginning of seed development and decline at mid-maturation, while there is a biphasic accumulation of γ-glutamyl-S-methylcysteine, at early cotyledon and maturation stages. A possible model involves the formation of S-methylcysteine by cysteine synthase from O-acetylserine and methanethiol, whereas the majority of γ-glutamyl-S-methylcysteine may arise from S-methylhomoglutathione. Metabolite profiling during development and in genotypes differing in total S-methylcysteine accumulation showed that γ-glutamyl-S-methylcysteine accounts for most of the total S-methylcysteine in mature seed. Profiling of transcripts for candidate biosynthetic genes indicated that BSAS4;1 expression is correlated with both the developmental timing and levels of free S-methylcysteine accumulated, while homoglutathione synthetase (hGS) expression was correlated with the levels of γ-glutamyl-S-methylcysteine. Analysis of S-methylated phytochelatins by liquid chromatography and high resolution tandem mass spectrometry revealed only small amounts of homophytochelatin-2 with a single S-methylcysteine. The mitochondrial localization of phytochelatin synthase 2—predominant in seed, determined by confocal microscopy of a fusion with the yellow fluorescent protein—and its spatial separation from S-methylhomoglutathione may explain the lack of significant accumulation of S-methylated phytochelatins. MDPI 2019-05-14 /pmc/articles/PMC6572574/ /pubmed/31091711 http://dx.doi.org/10.3390/plants8050126 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Saboori-Robat, Elham Joshi, Jaya Pajak, Aga Solouki, Mahmood Mohsenpour, Motahhareh Renaud, Justin Marsolais, Frédéric Common Bean (Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide |
title | Common Bean (Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide |
title_full | Common Bean (Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide |
title_fullStr | Common Bean (Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide |
title_full_unstemmed | Common Bean (Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide |
title_short | Common Bean (Phaseolus vulgaris L.) Accumulates Most S-Methylcysteine as Its γ-Glutamyl Dipeptide |
title_sort | common bean (phaseolus vulgaris l.) accumulates most s-methylcysteine as its γ-glutamyl dipeptide |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572574/ https://www.ncbi.nlm.nih.gov/pubmed/31091711 http://dx.doi.org/10.3390/plants8050126 |
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