Dynamics of methionine biosynthesis

Goto, Derek B.; Onouchi, Hitoshi; Naito, Shuichi

doi:10.5511/plantbiotechnology.22.379

Cited by 6 publications

(8 citation statements)

References 62 publications

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“…After a 72 h period of treatment, the 53-and 50-kD CGS bands were not detected but the CGS antiserum cross-reacted with a polypeptide of 43 6 1 kD. The accumulation of CGS polypeptides at 48 h could be attributed to a perturbation of the AdoMet-dependent feedback regulation of the expression of the CGS1 gene (Goto et al, 2005). Indeed, we can assume that the decrease in AdoMet level in MTXS cells (9 nmol g 21 FW at 48 h versus 28 nmol g 21 FW in control cells, see Fig.…”

Section: Expression Of Met-synthesizing Enzymes In Folate-deficient Cmentioning

confidence: 87%

“…Second, the N terminus of CGS is probably structurally disordered because (1) it is not visible in the electron density map (Steegborn et al, 1999), and (2) heat denaturation of the enzyme does not abolish CGS recognition and processing by the protease(s). Third, the only part of the N-terminal domain that is highly conserved among plant CGSs, the MTO1 domain (Goto et al, 2005), is not necessary for recognition of the enzyme by the proteolytic system, although it may be requested for the regulatory function of the N-terminal domain of CGS. Last, although the cleavage site is not canonical, the proteases expressed in response to folate starvation in different plant sources (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…The mature (MCGS) and cleaved (CCGS) versions of the Arabidopsis enzyme start with residues Val-69 and Ser-161, respectively. The MTO1 (Goto et al, 2005) and catalytic (Steegborn et al, 1999) domains are underlined. The truncated Arabidopsis CGS enzyme overexpressed in transgenic tobacco plants by Hacham et al (2002) starts with Ser-173 (asterisk).…”

Section: Comparison Of the Kinetic Properties Of Mcgs And Ccgsmentioning

confidence: 99%

“…1). Until now, four regulatory mechanisms have been implicated in the maintenance of Met and AdoMet homeostasis in plant cells (Goto et al, 2005). The first two processes allow a fine regulation of the metabolic flux to Met and Thr syntheses, the first two enzymes of these pathways, namely CGS and Thr synthase, competing for a common substrate, O-phosphohomo-Ser (OPH).…”

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confidence: 99%

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Regulation of One-Carbon Metabolism in Arabidopsis: The N-Terminal Regulatory Domain of Cystathionine γ-Synthase Is Cleaved in Response to Folate Starvation

et al. 2007

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In all organisms, control of folate homeostasis is of vital importance to sustain the demand for one-carbon (C1) units that are essential in major metabolic pathways. In this study we induced folate deficiency in Arabidopsis (Arabidopsis thaliana) cells by using two antifolate inhibitors. This treatment triggered a rapid and important decrease in the pool of folates with significant modification in the distribution of C1-substituted folate coenzymes, suggesting an adaptive response to favor a preferential shuttling of the flux of C1 units to the synthesis of nucleotides over the synthesis of methionine (Met). Metabolic profiling of folate-deficient cells indicated important perturbation of the activated methyl cycle because of the impairment of Met synthases that are deprived of their substrate 5-methyl-tetrahydrofolate. Intriguingly, S-adenosyl-Met and Met pools declined during the initial period of folate starvation but were further restored to typical levels. Reestablishment of Met and S-adenosylMet homeostasis was concomitant with a previously unknown posttranslational modification that consists in the removal of 92 amino acids at the N terminus of cystathionine g-synthase (CGS), the first specific enzyme for Met synthesis. Rescue experiments and analysis of different stresses indicated that CGS processing is specifically associated with perturbation of the folates pool. Also, CGS processing involves chloroplastic serine-type proteases that are expressed in various plant species subjected to folate starvation. We suggest that a metabolic effector, to date unidentified, can modulate CGS activity in vivo through an interaction with the N-terminal domain of the enzyme and that removal of this domain can suppress this regulation.

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Section: Expression Of Met-synthesizing Enzymes In Folate-deficient Cmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Comparison Of the Kinetic Properties Of Mcgs And Ccgsmentioning

confidence: 99%

mentioning

confidence: 99%

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Regulation of One-Carbon Metabolism in Arabidopsis: The N-Terminal Regulatory Domain of Cystathionine γ-Synthase Is Cleaved in Response to Folate Starvation

et al. 2007

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“…A. thaliana mto1 mutants that bear single amino acid sequence alterations within the MTO1 region abolish this feedback regulation, resulting in an over-accumulation of soluble Met (Ominato et al, 2002; for review, see Goto et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

A halt in poly(A) shortening during S-adenosyl-L-methionine-induced translation arrest in CGS1 mRNA of Arabidopsis thaliana

et al. 2013

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Cystathionine γ-synthase (CGS) catalyzes the first committed step of methionine (Met) biosynthesis in plants. Expression of the Arabidopsis thaliana CGS1 gene is negatively feedback-regulated in response to the direct Met metabolite S-adenosyl-L-methionine (AdoMet). This regulation occurs at the step of mRNA stability during translation and is coupled with AdoMet-induced CGS1-specific translation arrest. In general, mRNA decay is initiated by a shortening of the poly(A) tail. However, this process has not been studied in detail in cases where regulatory events, such as programmed translation arrest, are involved. Here, we report that the poly(A) tail of the full-length CGS1 mRNA showed an apparent increase from 50-80 nucleotides (nt) to 140-150 nt after the induction of CGS1 mRNA degradation. This finding was unexpected because mRNAs that are destined for degradation harbored longer poly(A) tail than mRNAs that were not targeted for degradation. The results suggest that poly(A) shortening is inhibited or delayed during AdoMet-induced translation arrest of CGS1 mRNA. We propose an explanation for this phenomenon that remains consistent with the recent model of actively translating mRNA. We also found that CGS1 mRNA degradation intermediates, which are 5'-truncated forms of CGS1 mRNA, had a short poly(A) tail of 10-30 nt. This suggests that poly(A) shortening occurs rapidly on the degradation intermediates. The present study highlights CGS1 mRNA degradation as a useful system to understand the dynamic features of poly(A) shortening.

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Comparative metabolomics charts the impact of genotype-dependent methionine accumulation in Arabidopsis thaliana

et al. 2010

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Methionine (Met) is an essential amino acid for all organisms. In plants, Met also functions as a precursor of plant hormones, polyamines, and defense metabolites. The regulatory mechanism of Met biosynthesis is highly complex and, despite its great importance, remains unclear. To investigate how accumulation of Met influences metabolism as a whole in Arabidopsis, three methionine over-accumulation (mto) mutants were examined using a gas chromatography-mass spectrometry-based metabolomics approach. Multivariate statistical analyses of the three mto mutants (mto1, mto2, and mto3) revealed distinct metabolomic phenotypes. Orthogonal projection to latent structures-discriminant analysis highlighted discriminative metabolites contributing to the separation of each mutant and the corresponding control samples. Though Met accumulation in mto1 had no dramatic effect on other metabolic pathways except for the aspartate family, metabolite profiles of mto2 and mto3 indicated that several extensive pathways were affected in addition to over-accumulation of Met. The pronounced changes in metabolic pathways in both mto2 and mto3 were associated with polyamines. The findings suggest that our metabolomics approach not only can reveal the impact of Met over-accumulation on metabolism, but also may provide clues to identify crucial pathways for regulation of metabolism in plants.

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Dynamics of methionine biosynthesis

Cited by 6 publications

References 62 publications

Regulation of One-Carbon Metabolism in Arabidopsis: The N-Terminal Regulatory Domain of Cystathionine γ-Synthase Is Cleaved in Response to Folate Starvation

Regulation of One-Carbon Metabolism in Arabidopsis: The N-Terminal Regulatory Domain of Cystathionine γ-Synthase Is Cleaved in Response to Folate Starvation

A halt in poly(A) shortening during <i>S</i>-adenosyl-L-methionine-induced translation arrest in <i>CGS1</i> mRNA of <i>Arabidopsis thaliana</i>

Comparative metabolomics charts the impact of genotype-dependent methionine accumulation in Arabidopsis thaliana

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