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A peptide inhibiting the collagen binding function of integrin alpha2I domain
J Ivaska1, J Käpylä, O Pentikäinen
1MediCity Research Laboratory, University of Turku, Finland.
The Journal of Biological Chemistry
|January 28, 1999
Summary
A novel cyclic peptide from snake venom inhibits integrin alpha2beta1 binding to extracellular matrix proteins like collagen. This peptide, containing an RKK motif, shows promise for targeting integrin-mediated cell adhesion.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Integrin alpha2beta1 is a cell surface receptor that binds extracellular matrix molecules (collagens, laminin-1) and is crucial for cell adhesion.
- Jararhagin, a disintegrin/metalloproteinase from Bothrops jararaca venom, inhibits alpha2beta1 integrin-collagen interactions.
- Previous studies indicated crude venom could inhibit recombinant alpha2I domain binding to collagen.
Purpose of the Study:
- To investigate the inhibitory potential of jararhagin-derived peptides on the interaction between the integrin alpha2I domain and its ligands.
- To identify the specific sequences and structural requirements for peptide-mediated inhibition of alpha2beta1 integrin function.
Main Methods:
- Synthesis of peptides representing sequences from jararhagin, including the RSECD motif and a basic peptide from the metalloproteinase domain.
- In vitro binding assays using human recombinant alpha2I domain and immobilized ligands (type I and IV collagens, laminin-1).
- Mutational analysis of the functional peptide and assessment of its conformation-dependent activity (cyclic vs. linear, Mg2+ dependence).
- Cell adhesion assays using cells expressing alpha2beta1 integrin.
Main Results:
- Synthetic peptides from the disintegrin-like domain did not inhibit ralpha2I domain binding to collagen.
- A cyclic peptide, CTRKKHDNAQC, from the metalloproteinase domain strongly bound to the ralpha2I domain and inhibited its interaction with collagen and laminin-1.
- Mutational analysis revealed the arginine-lysine-lysine (RKK) sequence as essential for binding.
- Peptide activity was dependent on its cyclic conformation, loop size, and the presence of Mg2+.
- Cell attachment to the peptide required alpha2beta1 integrin expression and was blocked by anti-integrin antibodies.
Conclusions:
- A cyclic peptide derived from jararhagin, containing an RKK motif, effectively inhibits alpha2beta1 integrin binding to collagen and laminin-1.
- The peptide's function is conformation-dependent and requires specific structural features, including the RKK sequence and Mg2+.
- This peptide represents a novel inhibitor of alpha2beta1 integrin function and offers a potential tool for studying integrin-mediated cell adhesion.