Proteomics and MALDI Bioinformatics
One-Sentence Definition
Proteomics and MALDI bioinformatics analyze mass-spectrometry signals to identify microorganisms and quantify their proteins.
Simple Explanation
Mass spectrometry weighs molecules; software turns those weights into “this is Staphylococcus aureus” or “this protein went up threefold.”
Detailed Scientific Explanation
Two related worlds:
- MALDI-TOF species ID (clinical routine) — whole-cell spectra of abundant ribosomal proteins matched against a reference spectral library; score thresholds decide genus/species confidence. Limits: closely related species (e.g., Shigella/E. coli, some streptococci), database coverage, extraction method.
- Shotgun proteomics (research) — protein digest → LC-MS/MS → spectra matched to a predicted proteome from Genome Annotation → FDR control via target-decoy → quantification (label-free, TMT).
Emerging: machine learning on raw spectra for resistance detection (e.g., carbapenemase-related peaks, MRSA-related profiles) — see AI Diagnostics in Microbiology.
Mechanism
Peak picking and alignment → similarity scoring against reference spectra or in silico peptide fragmentation matching.
Clinical Importance
- MALDI-TOF collapsed identification time from ~24 h to minutes; a major driver of faster targeted therapy and stewardship
Research Importance
- Post-transcriptional regulation, PTMs, secretomes, host–pathogen interfaces
Diagnostic Relevance
- Core technology of modern Culture and Isolation workflows and positive blood-culture pipelines
AMR Relevance
- Spectral ML for resistance prediction; direct detection of hydrolysis products for β-lactamase activity assays
Related MOCs
Active Recall Questions
- Which proteins dominate MALDI-TOF species spectra?
- Name two species pairs MALDI struggles to separate.
- What is target-decoy FDR in proteomics?