Fig 6.

BB0172 is an integrin-binding protein. (A) Purified BB0172_T was incubated with different ECM components: aggrecan, collagen I and IV, decorin, elastin, laminin, fibrinogen, human plasma fibronectin, human tissue fibronectin, and vitronectin. Recombinant BBK32 was used as a borrelial positive-control protein for the binding to human plasma fibronectin. (B) The binding of BB0172 to different integrins by using HBS buffer containing Ca²⁺, Mg²⁺, and Mn²⁺. Recombinant P66 was used as a positive control for the binding to human integrins. BB0172 bound more strongly to α₃β₁ integrin compared with the P66 binding. (C) Purified recombinant BB0172 proteins containing mutations in the MIDAS motif (AXSXS, DXAX, DXSXA, and AXAXA) were incubated with α₃β₁ integrin. BB0172T corresponds to the wild-type sequence. Each mutation of the MIDAS motif altered efficacy of the binding of BB0172 to α₃β₁ integrin. *, P < 0.05; **, P < 0.01; ***, P < 0.001 (compared with the control protein). All binding assays entailed four replicates for each protein in each ECM component or integrin.