- Madeleine Ernst (2)
- Louis Felix Nothias (1)
- Marnix H. Medema (1)
- Justin J.J. Hooft Van Der (2)
- Justin J.J. Hooft van der (1)
- Andrés Mauricio Caraballo-Rodríguez (1)
- Lars Ridder (1)
- Simon Rogers (3)
- Joe Wandy (3)
- Mingxun Wang (1)
- Cher Wei Ong (1)
- Stefan Weidt (1)
In silico optimization of mass spectrometry fragmentation strategies in metabolomics
Wandy, Joe ; Davies, Vinny ; Hooft, Justin J.J. Van Der; Weidt, Stefan ; Daly, R. ; Rogers, Simon - \ 2019
Metabolites 9 (2019)10. - ISSN 2218-1989
Data-dependent acquisition (DDA) - Fragmentation (MS/MS) - In silico - Liquid chromatography–mass spectrometry (LC/MS) - Simulator
Liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) is widely used in identifying small molecules in untargeted metabolomics. Various strategies exist to acquire MS/MS fragmentation spectra; however, the development of new acquisition strategies is hampered by the lack of simulators that let researchers prototype, compare, and optimize strategies before validations on real machines. We introduce Virtual Metabolomics Mass Spectrometer (ViMMS), a metabolomics LC-MS/MS simulator framework that allows for scan-level control of the MS2 acquisition process in silico. ViMMS can generate new LC-MS/MS data based on empirical data or virtually re-run a previous LC-MS/MS analysis using pre-existing data to allow the testing of different fragmentation strategies. To demonstrate its utility, we show how ViMMS can be used to optimize N for Top-N data-dependent acquisition (DDA) acquisition, giving results comparable to modifying N on the mass spectrometer. We expect that ViMMS will save method development time by allowing for offline evaluation of novel fragmentation strategies and optimization of the fragmentation strategy for a particular experiment.
Molnetenhancer: Enhanced molecular networks by integrating metabolome mining and annotation tools
Ernst, Madeleine ; Kang, Kyo Bin ; Caraballo-Rodríguez, Andrés Mauricio ; Nothias, Louis Felix ; Wandy, Joe ; Chen, Christopher ; Wang, Mingxun ; Rogers, Simon ; Medema, Marnix H. ; Dorrestein, Pieter C. ; Hooft, Justin J.J. van der - \ 2019
Metabolites 9 (2019)7. - ISSN 2218-1989
Chemical classification - In silico workflows - Metabolite annotation - Metabolite identification - Metabolome mining - Molecular families - Networking - Substructures
Metabolomics has started to embrace computational approaches for chemical interpretation of large data sets. Yet, metabolite annotation remains a key challenge. Recently, molecular networking and MS2LDA emerged as molecular mining tools that find molecular families and substructures in mass spectrometry fragmentation data. Moreover, in silico annotation tools obtain and rank candidate molecules for fragmentation spectra. Ideally, all structural information obtained and inferred from these computational tools could be combined to increase the resulting chemical insight one can obtain from a data set. However, integration is currently hampered as each tool has its own output format and efficient matching of data across these tools is lacking. Here, we introduce MolNetEnhancer, a workflow that combines the outputs from molecular networking, MS2LDA, in silico annotation tools (such as Network Annotation Propagation or DEREPLICATOR), and the automated chemical classification through ClassyFire to provide a more comprehensive chemical overview of metabolomics data whilst at the same time illuminating structural details for each fragmentation spectrum. We present examples from four plant and bacterial case studies and show how MolNetEnhancer enables the chemical annotation, visualization, and discovery of the subtle substructural diversity within molecular families. We conclude that MolNetEnhancer is a useful tool that greatly assists the metabolomics researcher in deciphering the metabolome through combination of multiple independent in silico pipelines.
Deciphering complex metabolite mixtures by unsupervised and supervised substructure discovery and semi-automated annotation from MS/MS spectra
Rogers, Simon ; Wei Ong, Cher ; Wandy, Joe ; Ernst, Madeleine ; Ridder, Lars ; Hooft, Justin J.J. Van Der - \ 2019
Faraday Discussions 218 (2019). - ISSN 1359-6640 - p. 284 - 302.
Complex metabolite mixtures are challenging to unravel. Mass spectrometry (MS) is a widely used and sensitive technique to obtain structural information on complex mixtures. However, just knowing the molecular masses of the mixture’s constituents is almost always insufficient for confident assignment of the associated chemical structures. Structural information can be augmented through MS fragmentation experiments whereby detected metabolites are fragmented giving rise to MS/MS spectra. However, how can we maximize the structural information we gain from fragmentation spectra? We recently proposed a substructure-based strategy to enhance metabolite annotation for complex mixtures by considering metabolites as the sum of (bio)chemically relevant moieties that we can detect through mass spectrometry fragmentation approaches. Our MS2LDA tool allows us to discover - unsupervised - groups of mass fragments and/or neutral losses termed Mass2Motifs that often correspond to substructures. After manual annotation, these Mass2Motifs can be used in subsequent MS2LDA analyses of new datasets, thereby providing structural annotations for many molecules that are not present in spectral databases. Here, we describe how additional strategies, taking advantage of i) combinatorial in-silico matching of experimental mass features to substructures of candidate molecules, and ii) automated machine learning classification of molecules, can facilitate semi-automated annotation of substructures. We show how our approach accelerates the Mass2Motif annotation process and therefore broadens the chemical space spanned by characterized motifs. Our machine learning model used to classify fragmentation spectra learns the relationships between fragment spectra and chemical features. Classification prediction on these features can be aggregated for all molecules that contribute to a particular Mass2Motif and guide Mass2Motif annotations. To make annotated Mass2Motifs available to the community, we also present motifDB: an open database of Mass2Motifs that can be browsed and accessed programmatically through an API. MotifDB is integrated within ms2lda.org, allowing users to efficiently search for characterized motifs in their own experiments. We expect that with an increasing number of Mass2Motif annotations available through a growing database we can more quickly gain insight in the constituents of complex mixtures. That will allow prioritization towards novel or unexpected chemistries and faster recognition of known biochemical building blocks.