CCR7 Sulfotyrosine Enhances CCL21 Binding

Area of Science:

• Immunology and Molecular Biology
• Protein-ligand interactions
• Drug discovery targets

Background:

• Chemokines like CCL21 and CCL19 are crucial for immune cell trafficking to lymph nodes.
• Chemokine receptor CCR7 is implicated in the metastasis of certain cancers.
• N-terminal posttranslational modifications, especially tyrosine sulfation, can modulate chemokine receptor affinity.

Purpose of the Study:

• To investigate the binding interactions between CCL21 and modified CCR7 peptides.
• To compare the effects of tyrosine, phosphotyrosine (pY), and sulfotyrosine (sY) modifications on CCR7 binding affinity.
• To explore the potential of chemokine sulfotyrosine binding sites as drug development targets.

Main Methods:

• Utilized protein Nuclear Magnetic Resonance (NMR) spectroscopy.
• Compared the binding of CCL21 to various N-terminal CCR7 peptide fragments.
• Included peptides with unmodified tyrosine (Y), phosphotyrosine (pY), and sulfotyrosine (sY) at specific positions (Y8 and Y17).

Main Results:

• Specific binding sites were identified for CCR7 peptides near the α-helix (Y8) and the N-loop/β3-strand (Y17) of CCL21.
• All modified CCR7 peptides (pY and sY) exhibited enhanced binding affinity to CCL21 compared to unmodified tyrosine.
• Sulfotyrosine (sY) modification demonstrated the most significant increase in binding affinity to CCL21.

Conclusions:

• Tyrosine sulfation is a key posttranslational modification enhancing CCR7-CCL21 binding affinity.
• The findings highlight the structural basis for differential binding and receptor-ligand bias.
• Chemokine sulfotyrosine binding sites represent promising targets for therapeutic intervention in diseases involving immune cell migration.