Fig. S1.

Sawtooth force profiles suggest zipper-like cell–cell adhesion. (A) Representative force curves between L. lactis SdrC⁽⁺⁾ cells, displaying sawtooth profiles with up to 12 force peaks. (B) Peak-to-peak distance histogram documenting a sharp maximum at 25 nm that cannot be ascribed to the unfolding of single SdrC subdomains. (C) Proposed model for zipper-like adhesion. Periodic force peaks may correspond to the mechanical unzipping of homophilic interactions formed between ordered SdrC surfaces. Following the formation of single trans interactions, the lateral assembly (cis interactions) on the cell surface would enhance cell–cell adhesion.