A platform for mapping reactive cysteines within the immunopeptidome

NU 2024-044

INVENTORS

• Xiaoyu Zhang*
• Chenlu Zhang
• Chen Zhou

SHORT DESCRIPTION

This invention provides novel chemical probes for mapping reactive cysteine residues within the major histocompatibility complex class I (MHC-I) immunopeptidome.

BACKGROUND

The immune system's recognition of infected or malignant cells hinges on the presentation of peptide antigens by MHC-I molecules. A significant subset of these MHC-I-bound peptides contains cysteine residues, whose therapeutic importance, especially in cancer immunotherapy, is increasingly recognized. Despite this, the reactivity and functional roles of these cysteines within the immunopeptidome, along with their accessibility for therapeutic targeting, remain poorly understood. Existing computational tools for predicting antigen-MHC-I binding often struggle to accurately model antigens containing cysteine residues, leaving a critical unmet need for a systematic approach to map and characterize the reactive cysteines on cell-surface presented peptides.

ABSTRACT

Northwestern researchers designed novel chemical probes that selectively label extracellular cysteine residues on antigens presented by MHC-I molecules. These probes are technically characterized by three essential features: they are cell-impermeable, ensuring spatial specificity by exclusively targeting extracellular cysteines; they exhibit residue specificity, reacting solely with cysteine residues; and they enable quantification by introducing unique chemical modifications detectable via analytical techniques such as flow cytometry, fluorometric assays, and mass spectrometry. This allows for precise measurement of cysteine reactivity and abundance, providing a robust tool to investigate the functional roles of cysteines in antigen presentation and overcoming limitations of current computational prediction methods.

Schematic representation of the reactivity-based antigen profiling workflow

APPLICATIONS

• Therapeutic target discovery and drug development leveraging reactive cysteines on MHC-I presented antigens
• Biomarker discovery to uncover reactive cysteines displayed in different conditions or treatment settings
• Research reagent for identifying reactive cysteines

ADVANTAGES

• Enhanced detection and precise mapping of reactive cysteines
• Improved quantification of cysteine reactivity
• Selective extracellular labeling
• Compatibility with multiple analytical techniques

PUBLICATIONS

• Zhang et al, A platform for mapping reactive cysteines within the immunopeptidome, 2024.

IP STATUS

A US non-provisional patent has been filed.