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Publication Abstract from PubMed

Targeting both integrins alphaVbeta3 and alpha5beta1 simultaneously appears to be more effective in cancer therapy than targeting each one alone. The structural requirements for bispecific binding of ligand to integrins have not been fully elucidated. RGD-containing knottin 2.5F binds selectively to alphaVbeta3 and alpha5beta1, whereas knottin 2.5D is alphaVbeta3 specific. To elucidate the structural basis of this selectivity, we determined the structures of 2.5F and 2.5D as apo proteins and in complex with alphaVbeta3, and compared their interactions with integrins using molecular dynamics simulations. These studies show that 2.5D engages alphaVbeta3 by an induced fit, but conformational selection of a flexible RGD loop accounts for high-affinity selective binding of 2.5F to both integrins. The contrasting binding of the highly flexible low-affinity linear RGD peptides to multiple integrins suggests that a "Goldilocks zone" of conformational flexibility of the RGD loop in 2.5F underlies its selective binding promiscuity to integrins.

Structural Basis of the Differential Binding of Engineered Knottins to Integrins alphaVbeta3 and alpha5beta1.,Van Agthoven JF, Shams H, Cochran FV, Alonso JL, Kintzing JR, Garakani K, Adair BD, Xiong JP, Mofrad MRK, Cochran JR, Arnaout MA Structure. 2019 Sep 3;27(9):1443-1451.e6. doi: 10.1016/j.str.2019.06.011. Epub, 2019 Jul 25. PMID:31353240^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.