HolobiomicsLab 
lipid-a-structure-annotation
Summary
LipidA-IDER is an automated structure annotation tool for systems-level identification of lipid A from high-resolution tandem mass spectrometry (MS2) data. Use this skill to assign lipid A molecular structures to fragmentation patterns in MS2 spectra.
When to use
When you have high-resolution tandem mass spectrometry (MS2) data in .ms2 format and need to identify and annotate lipid A structures at scale. Suitable for researchers working with lipopolysaccharide components or bacterial lipid extracts where lipid A structural diversity must be characterized.
When NOT to use
- Input data is not in .ms2 format (first convert using MSConvert with CWT peak-picking and MS level 2 filtering)
- Running on macOS or Linux (tool has only been tested on Windows; use on other platforms is untested)
- You require real-time or interactive visualization of fragmentation trees (CLI mode provides only batch output)
Inputs
- .ms2 format mass spectrometry data files
- LipidAIDER_AnalysisParam.csv parameter configuration file
- optional: LipidAIDER_BatchAnalysisFiles.csv for batch submission
Outputs
- annotated lipid A structure identifications
- fragmentation pattern interpretations
- batch output files in Logger/YYYYMMDD_HHMMSS/Batch Output directory
How to apply
Install the LipidA-IDER repository and set up the Python environment. Prepare input .ms2 files (converted from raw instrument data using MSConvert with peak-picking algorithm CWT and MS level 2 filtering). Configure analysis parameters in LipidAIDER_AnalysisParam.csv according to your MS data characteristics (e.g., mass tolerance, fragmentation thresholds). Execute the annotation via GUI (python LipidAIDER_GUI.py) or CLI (python LIPIDAIDER_main.py) against your prepared .ms2 files or the provided demo_input_files. The tool will generate annotated lipid A structure assignments with fragmentation interpretations in the timestamped output directory (Logger/YYYYMMDD_HHMMSS/Batch Output).
Related tools
- MSConvert (ProteoWizard) (converts raw mass spectrometry instrument data to .ms2 format with peak-picking (CWT algorithm) and MS level 2 filtering required by LipidA-IDER) — https://proteowizard.sourceforge.io/download.html
- Python (runtime environment for executing LipidAIDER_GUI.py and LIPIDAIDER_main.py scripts)
- git (version control for cloning the LipidA-IDER repository from GitHub) — https://github.com/git-guides/install-git
Examples
$ python LIPIDAIDER_main.py -m /path/to/sample.ms2
Evaluation signals
- Output directory is successfully created with timestamp format YYYYMMDD_HHMMSS and contains Batch Output subfolder
- Generated lipid A structure annotations correspond to known fragmentation patterns in the MS2 spectra
- All input .ms2 files are processed without errors; completion is indicated by output file generation
- Parameter configuration matches data characteristics (e.g., mass tolerance aligns with instrument specifications)
- Annotated structures have consistent mass-to-charge ratios and fragment ion assignments with input spectral peaks
Limitations
- LipidA-IDER has only been tested on Windows; use on macOS and Linux has not been tested
- Currently accepts .ms2 format data files only; raw instrument data must be pre-converted via MSConvert
- Annotation accuracy depends on quality of input .ms2 file preparation and appropriate parameter tuning for the specific MS instrument and lipid A sample type
- No changelog is available to track tool version changes or improvements
Evidence
- [readme] LipidA-IDER is an automated structure annotation tool for systems-level scale identification of lipid A from high resolution tandem mass spectrometry (MS2) data: "LipidA-IDER is an automated structure annotation tool for systems-level scale identification of lipid A from high resolution tandem mass spectrometry (MS2) data"
- [readme] Input file format requirement: "LipidAIDER currently accepts data in .ms2 format. To convert to .ms2, use MSConvert (ProteoWizard)"
- [readme] Demo files availability for users without MS2 data: "In the event that you do not have initial .ms2 data, we have provided the some demo input files for your use here: [\Source\demo_input_files]"
- [readme] Output location convention: "Upon completion of the analysis. the generated output will be found in the '\Logger<YYYYMMDD_HHMMSS>\Batch Output' subfolder."
- [readme] Platform limitation: "As of current, LipidA-IDER has only been tested on Windows. Use of LipidA-IDER on MacOS and Linux has not been tested."
- [readme] Parameter configuration requirement: "Users may edit this file to according to the nature of their data. The default settings for Lipid A has been recorded in [\Settings\README.md]"
- [readme] GUI execution command: "$ python LipidAIDER_GUI.py"