Bioassay‐directed fractionation for discovery of bioactive neutral lipids guided by relative mass defect filtering and multiplexed collision‐induced dissociation

Stagliano, Michael C.; DeKeyser, Joshua G.; Omiecinski, Curtis J.; Jones, A. Daniel

doi:10.1002/rcm.4796

Cited by 20 publications

(12 citation statements)

References 32 publications

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“…Since absolute mass defect largely reflects the total hydrogen content, RMD serves as a measure of fractional hydrogen content (Stagliano et al, 2010), which in turn reflects the reduced state of carbon that derives from the contributions of metabolic precursors. RMD is calculated in ppm as (mass defect/measured monoisotopic mass) 3 10 6 .…”

Section: Foundations Of Relative Mass Defect Filtering For Mining Plamentioning

confidence: 99%

Relative Mass Defect Filtering of Mass Spectra: A Path to Discovery of Plant Specialized Metabolites

2015

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The rapid identification of novel plant metabolites and assignments of newly discovered substances to natural product classes present the main bottlenecks to defining plant specialized phenotypes. Although mass spectrometry provides powerful support for metabolite discovery by measuring molecular masses, ambiguities in elemental formulas often fail to reveal the biosynthetic origins of specialized metabolites detected using liquid chromatography-mass spectrometry. A promising approach for mining liquid chromatography-mass spectrometry metabolite profiling data for specific metabolite classes is achieved by calculating relative mass defects (RMDs) from molecular and fragment ions. This strategy enabled the rapid recognition of an extensive range of terpenoid metabolites in complex plant tissue extracts and is independent of retention time, abundance, and elemental formula. Using RMD filtering and tandem mass spectrometry data analysis, 24 novel elemental formulas corresponding to glycosylated sesquiterpenoid metabolites were identified in extracts of the wild tomato Solanum habrochaites LA1777 trichomes. Extensive isomerism was revealed by ultra-high-performance liquid chromatography, leading to evidence of more than 200 distinct sesquiterpenoid metabolites. RMD filtering led to the recognition of the presence of glycosides of two unusual sesquiterpenoid cores that bear limited similarity to known sesquiterpenes in the genus Solanum. In addition, RMD filtering is readily applied to existing metabolomics databases and correctly classified the annotated terpenoid metabolites in the public metabolome database for Catharanthus roseus.Plant metabolic networks generate amazing chemical diversity, but our understanding of the genetic factors responsible for plant chemistry remains primitive. The discovery and identification of metabolites has posed the greatest bottleneck in recent efforts to exploit metabolomics to address questions about the basis for biosynthetic diversity in the plant kingdom (Ji et al., 2009;Zhou et al., 2012). Since the specialized metabolism of nonmodel plants is taxonomically restricted, metabolite databases offer a poor representation of plant chemical diversity, and de novo recognition and discovery of metabolite chemistry is necessary. A common strategy for metabolite discovery has often started with the generation of tandem mass spectrometry (MS/MS) spectra, usually beginning with the most abundant metabolites, and uses characteristic fragment ions to assign metabolites to a particular class of compounds. Flavonoid identification from MS/MS spectra is often successful because most flavonoids yield MS/MS fragment ions characteristic of their flavonoid cores (Ma et al., 1997;Li et al., 2013). However, when MS/MS spectra fail to display classcharacteristic fragment ions, the recognition of a metabolite's structural class is less obvious.Specialized plant metabolites are often grouped as polyphenolic, terpenoid, alkaloid, polyketide, or fatty acid metabolites based upon the biosynthesis of their...

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Section: Foundations Of Relative Mass Defect Filtering For Mining Plamentioning

confidence: 99%

Relative Mass Defect Filtering of Mass Spectra: A Path to Discovery of Plant Specialized Metabolites

2015

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“…Mass spectra were acquired using W-mode ion optics (mass resolution at full-width half-maximum = 9000) using negative-ion mode electrospray ionization over m/z 100 to 2000. Mass spectra were acquired in five quasisimultaneous functions using aperture 1 potential settings of 20, 35, 50, 65, and 80 V to generate nonselective ion fragmentation using a protocol known as multiplexed collision-induced dissociation (Gu et al, 2010;Stagliano et al, 2010) that provides additional evidence of lipid structure from fragment ion masses. Levels of CL were quantified by integration (Waters QuanLynx software) of the extracted ion chromatogram for m/z 1401.98, corresponding to [M-H] 2 of the most abundant form of CL (with two 16-carbon and two 18-carbon fatty acids and a total of three double bonds).…”

Section: Lc-ms Analysismentioning

confidence: 99%

Cardiolipin-Mediated Mitochondrial Dynamics and Stress Response inArabidopsis

Pan

Jones

2014

The Plant Cell

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Mitochondria are essential and dynamic organelles in eukaryotes. Cardiolipin (CL) is a key phospholipid in mitochondrial membranes, playing important roles in maintaining the functional integrity and dynamics of mitochondria in animals and yeasts. However, CL's role in plants is just beginning to be elucidated. In this study, we used Arabidopsis thaliana to examine the subcellular distribution of CL and CARDIOLIPIN SYNTHASE (CLS) and analyzed loss-of-function cls mutants for defects in mitochondrial morphogenesis and stress response. We show that CL localizes to mitochondria and is enriched at specific domains, and CLS targets to the inner membrane of mitochondria with its C terminus in the intermembrane space. Furthermore, cls mutants exhibit significantly impaired growth as well as altered structural integrity and morphogenesis of mitochondria. In contrast to animals and yeasts, in which CL's effect on mitochondrial fusion is more profound, Arabidopsis CL plays a dominant role in mitochondrial fission and exerts this function, at least in part, through stabilizing the protein complex of the major mitochondrial fission factor, DYNAMIN-RELATED PROTEIN3. CL also plays a role in plant responses to heat and extended darkness, stresses that induce programmed cell death. Our study has uncovered conserved and plant-specific aspects of CL biology in mitochondrial dynamics and the organism response to environmental stresses.

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“…The mass defect of the ions, the digits of the mass value that follow the decimal point, was also used to categorize the type of compound represented by each analytical signal. The relative mass defect, which is the defect normalized to the measured mass, largely reflects the hydrogen content of the ionized molecule (Last et al, 2007;Stagliano et al, 2010).…”

Section: Overview Of the Approachmentioning

confidence: 99%

Striking Natural Diversity in Glandular Trichome Acylsugar Composition Is Shaped by Variation at the Acyltransferase2 Locus in the Wild Tomato Solanum habrochaites

Kim¹,

Kang²,

Gonzales‐Vigil³

et al. 2012

Plant Physiology

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Acylsugars are polyesters of short-to medium-length acyl chains on sucrose or glucose backbones that are produced in secretory glandular trichomes of many solanaceous plants, including cultivated tomato (Solanum lycopersicum). Despite their roles in biotic stress adaptation and their wide taxonomic distribution, there is relatively little information about the diversity of these compounds and the genes responsible for their biosynthesis. In this study, acylsugar diversity was assessed for 80 accessions of the wild tomato species Solanum habrochaites from throughout the Andes Mountains. Trichome metabolites were analyzed by liquid chromatography-time of flight-mass spectrometry, revealing the presence of at least 34 structurally diverse acylsucroses and two acylglucoses. Distinct phenotypic classes were discovered that varied based on the presence of glucose or sucrose, the numbers and lengths of acyl chains, and the relative total amounts of acylsugars. The presence or absence of an acetyl chain on the acylsucrose hexose ring caused clustering of the accessions into two main groups. Analysis of the Acyltransferase2 gene (the apparent ortholog of Solyc01g105580) revealed differences in enzyme activity and gene expression correlated with polymorphism in S. habrochaites accessions that varied in acylsucrose acetylation. These results are consistent with the hypothesis that glandular trichome acylsugar acetylation is under selective pressure in some populations of S. habrochaites and that the gene mutates to inactivity in the absence of selection.

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Bioassay‐directed fractionation for discovery of bioactive neutral lipids guided by relative mass defect filtering and multiplexed collision‐induced dissociation

Cited by 20 publications

References 32 publications

Relative Mass Defect Filtering of Mass Spectra: A Path to Discovery of Plant Specialized Metabolites

Relative Mass Defect Filtering of Mass Spectra: A Path to Discovery of Plant Specialized Metabolites

Cardiolipin-Mediated Mitochondrial Dynamics and Stress Response inArabidopsis

Striking Natural Diversity in Glandular Trichome Acylsugar Composition Is Shaped by Variation at the Acyltransferase2 Locus in the Wild Tomato Solanum habrochaites

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