Deciphering RGDechi peptide-a5b1 integrin interaction mode in isolated cell membranes

Integrins are a large family of heterodimeric receptors critically engaged in pathological processes such as tumor progression and metastasis. Although they are validated therapeutic targets, the molecular determinants governing integrin-ligand interactions are not yet fully understood, leading to a scarcity of integrin sub-type exclusive antagonists. In the past decade, we have investigated the biological behavior of the RGDechi, a chimeric peptide able to specifically bind avb3 integrin without cross reacting with avb5 and aIIbb3 integrins. Here we have investigated the capability of the peptide to bind a5b1 integrin and characterized the molecular determinants governing this interaction through a combined experimental and computational approach. The detailed comparison of RGDechi-a5b1 structural model with that previously determined of RGDechi in complex with avb3 shows how the bifunctional nature of the peptide renders the molecule an important tool to recognize integrins with different recognition modalities, providing novel insight on the structural requirements needed to their specific recognition.