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Updated: Sep 27, 2026
Immunopeptidomics: Isolation of Mouse and Human MHC Class I- and II-Associated Peptides for Mass Spectrometry Analysis
Published on: October 15, 2021
Application of immunoproteomics to analysis of post-translational processing of the antiphagocytic M protein of
Terence G Romer1, Michael D P Boyle
1Department of Microbiology and Immunology, Medical College of Ohio, Toledo, OH, USA.
Abstract:
Post-translational modification of the antiphagocytic M1 protein of Streptococcus pyogenes can influence its binding properties for human immunoglobulin G subclasses and its invasive potential. Current methods of monitoring this modification event involve N-terminal sequencing and are cumbersome, slow and not amenable to routine analysis. In this study we demonstrate that surface enhanced laser desorption/ionization-time of flight mass spectrometry can be used to monitor modification of the M1 protein by the secreted bacterial cysteine protease, SpeB. This method, when combined with a specific antibody capture step provides a specific, rapid and sensitive assay for key virulence factors of the important human pathogen Streptococcus pyogenes.
Insights
A new mass spectrometry method rapidly monitors Streptococcus pyogenes M1 protein modification. This advance offers a faster, more sensitive assay for tracking key virulence factors in this important human pathogen.
Area of Science:
- Microbiology
- Proteomics
- Biochemistry
Background:
- The antiphagocytic M1 protein of Streptococcus pyogenes is crucial for virulence.
- Post-translational modification of M1 protein affects its interaction with human immunoglobulin G (IgG) subclasses and influences bacterial invasion.
- Existing methods for monitoring M1 protein modification, such as N-terminal sequencing, are time-consuming and not suitable for routine diagnostics.
Purpose of the Study:
- To develop a rapid, sensitive, and specific assay for monitoring M1 protein modification by the bacterial cysteine protease SpeB.
- To establish surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF MS) as a viable tool for analyzing M1 protein post-translational modifications.
Main Methods:
- Utilized surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF MS) to analyze M1 protein.
- Integrated a specific antibody capture step with SELDI-TOF MS for enhanced specificity.
- Investigated the modification of M1 protein by the secreted bacterial cysteine protease, SpeB.
Main Results:
- Demonstrated that SELDI-TOF MS can effectively monitor the modification of the M1 protein.
- The SELDI-TOF MS method, combined with antibody capture, provides a specific and sensitive detection of M1 protein modification.
- The assay successfully identified modifications mediated by the SpeB protease.
Conclusions:
- SELDI-TOF MS offers a rapid and sensitive alternative to traditional methods for monitoring M1 protein post-translational modifications.
- This technique facilitates the study of virulence factor modification in Streptococcus pyogenes.
- The developed assay is valuable for routine analysis of key virulence factors in this significant human pathogen.
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