Summary of Study ST001062

This data is available at the NIH Common Fund's National Metabolomics Data Repository (NMDR) website, the Metabolomics Workbench, https://www.metabolomicsworkbench.org, where it has been assigned Project ID PR000712. The data can be accessed directly via it's Project DOI: 10.21228/M8N965 This work is supported by NIH grant, U2C- DK119886.

See: https://www.metabolomicsworkbench.org/about/howtocite.php

Study ID	ST001062
Study Title	Arabidopsis Nit1 knockout metabolomics
Study Summary	Glutathione (GSH) is a tripeptide that is implicated in various crucial physiological processes including redox buffering and protection against heavy metal toxicity. GSH is abundant in plants, with reported intracellular concentrations typically in the 1-10 millimolar range. Various aminotransferases can inadvertently transaminate the amino group of the γ-glutamyl moiety of GSH to produce deaminated glutathione (dGSH), a metabolite damage product. It was recently reported that an amidase known as Nit1 participates in dGSH breakdown in mammals and yeast. Plants have a hitherto uncharacterized homolog of the Nit1 amidase. We show that recombinant Arabidopsis Nit1 (At4g08790) has efficient amidase activity towards dGSH. Ablating the Arabidopsis Nit1 gene causes a massive accumulation of dGSH and other marked changes to the metabolome. All plant Nit1 sequences examined had predicted plastidial targeting peptides with a potential second start codon whose use would eliminate the targeting peptide. In vitro transcription/translation assays show that both potential translation start codons were used and subcellular localization of GFP fusions confirmed both cytosolic and plastidial localization. Further, we show that Arabidopsis enzymes convert GSH to dGSH at a rate of 2.8 pmol min-1 mg-1 in vitro. Our data demonstrate that plants have a dGSH repair system that is directed to at least two subcellular compartments via the use of alternative translation start sites.
Institute	University of California, Davis
Last Name	Folz
First Name	Jacob
Address	451 Health Sciences Dr., Davis, CA, 95616
Email	jfolz@ucdavis.edu
Phone	7155636311
Submit Date	2018-09-24
Raw Data Available	Yes
Raw Data File Type(s)	raw(Thermo)
Analysis Type Detail	LC-MS
Release Date	2019-03-06
Release Version	1

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Sample Preparation:

Sampleprep ID:	SP001113
Sampleprep Summary:	Samples (10 mg lyophilized plant tissue) were extracted using biphasic extraction technique adapted from Matyash et al. 2008. In summary 225 µL LC-MS grade methanol was added to lyophilized plant tissue in 2 mL Eppendorf tube, vortexed for 10 seconds, followed by addition of 750 µL methyl tert-butyl ether (MTBE). Each sample was then vortexed for 10 seconds, shook on orbital shaker at maximum speed for six minutes, followed by addition of 188 µL LC-MS grade water. Finally, each sample was vortexed for 10 seconds and centrifuged for 2 minutes at 14,000 rpm. The resultant two-phase extract was aliquoted into four clean 1.5 mL Eppendorf tubes. The result was two 350 µL aliquots of MTBE phase (top), and two 110 µL aliquots of methanol/water phase (bottom). Extraction was carried out at 4°C. All extract tubes were dried under vacuum and frozen at -80°C until LC-MS/MS analysis. Lipidomics analysis followed methods of Cajka et al. 2017. Briefly, extract from one aliquot of MTBE phase was resuspended in 110 µL methanol/toluene (9:1, v/v), vortexed for 10 seconds, centrifuged for 2 minutes at 14,000 rpm, transferred to HPLC vial, and stored at 4°C until LC-MS/MS analysis. Gradient, internal standards, mobile phases, and data collection methods were identical to Cajka et al. 2017. Sample injection volume was 3 µL on a Waters Acquity UPLC CSH C18 column (100mm x 2.1mm, 1.7 μm particle size). A Thermo Vanquish Focused UHPLC system coupled to Thermo Q Exactive HF mass spectrometer was used for all untargeted analysis. Untargeted polar metabolomics analysis followed methods of Niehaus et al. 2018. Briefly, one aliquot of methanol/water phase extract was resuspended in 100 µL acetonitrile/water (4:1 v/v) with internal standards including 5 µg/ml Val-Tyr-Val. Analysis was carried out using Waters Acquity UPLC BEH Amide (150mm x 2.1 mm id, 1.7 μm particle size) column with identical mobile phase, gradient, injection volume, and data collection to Niehaus et al. 2018.

Sampleprep ID:

SP001113

Sampleprep Summary:

Samples (10 mg lyophilized plant tissue) were extracted using biphasic extraction technique adapted from Matyash et al. 2008. In summary 225 µL LC-MS grade methanol was added to lyophilized plant tissue in 2 mL Eppendorf tube, vortexed for 10 seconds, followed by addition of 750 µL methyl tert-butyl ether (MTBE). Each sample was then vortexed for 10 seconds, shook on orbital shaker at maximum speed for six minutes, followed by addition of 188 µL LC-MS grade water. Finally, each sample was vortexed for 10 seconds and centrifuged for 2 minutes at 14,000 rpm. The resultant two-phase extract was aliquoted into four clean 1.5 mL Eppendorf tubes. The result was two 350 µL aliquots of MTBE phase (top), and two 110 µL aliquots of methanol/water phase (bottom). Extraction was carried out at 4°C. All extract tubes were dried under vacuum and frozen at -80°C until LC-MS/MS analysis. Lipidomics analysis followed methods of Cajka et al. 2017. Briefly, extract from one aliquot of MTBE phase was resuspended in 110 µL methanol/toluene (9:1, v/v), vortexed for 10 seconds, centrifuged for 2 minutes at 14,000 rpm, transferred to HPLC vial, and stored at 4°C until LC-MS/MS analysis. Gradient, internal standards, mobile phases, and data collection methods were identical to Cajka et al. 2017. Sample injection volume was 3 µL on a Waters Acquity UPLC CSH C18 column (100mm x 2.1mm, 1.7 μm particle size). A Thermo Vanquish Focused UHPLC system coupled to Thermo Q Exactive HF mass spectrometer was used for all untargeted analysis. Untargeted polar metabolomics analysis followed methods of Niehaus et al. 2018. Briefly, one aliquot of methanol/water phase extract was resuspended in 100 µL acetonitrile/water (4:1 v/v) with internal standards including 5 µg/ml Val-Tyr-Val. Analysis was carried out using Waters Acquity UPLC BEH Amide (150mm x 2.1 mm id, 1.7 μm particle size) column with identical mobile phase, gradient, injection volume, and data collection to Niehaus et al. 2018.