
The binding of SxIP-containing ligands to the EB1 protein involves a two-step "dock-and-lock" mechanism, where the initial docking through the SxIP motif provides specificity, and the subsequent folding of the EB1 C-terminus defines the full binding affinity.


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End Binding protein 1 (EB1) is a key component of the signalling networks located at the plus ends of microtubules. It incorporates an N-terminal microtubule binding CH domain and the C-terminal EBH domain that interacts with the SxIP-containing sequences of other microtubule plus end tracking proteins (+TIPs). By using a series of SxIP containing peptides derived from the microtubule-actin cross-linking factor, MACF, we show that the SxIP motif itself binds to EBH with low affinity, and the full interaction requires contribution of the post-SxIP residues. Based on the solution structure and dynamics of the EBH/MACF complex we proposed a two-step ‘dock-and-lock’ model for the EBH interaction with targets, where the SxIP motif initially binds to a partially-formed EBH pocket, which subsequently induces folding of the unstructured C-terminus and transition to the stable complex. We dissect contributions from different interactions into the binding and design MACF mutations of the post-SxIP region that enhance the affinity by two orders of magnitude, leading to a nanomolar interaction. We verify the enhanced recruitment of the mutated peptide to the dynamic plus ends of MTs in a live cell experiment. Our model explains EB1’s interaction with the SxIP-containing ligands and can be used to design of small molecule inhibitors that can block SxIP interaction with EB1.

### Competing Interest Statement

The authors have declared no competing interest.

Dock-and-lock binding of SxIP ligands is required for stable and selective EB1 interactions

enhancing-the-binding-affinity-of-sxip-ligands-to-the-eb1-protein-through-rational-peptide-design


Enhancing the Binding Affinity of SxIP Ligands to the EB1 Protein through Rational Peptide Design
