Interacts specifically in a calcium-dependent manner with the acidic exopolysaccharide (EPS) and capsular polysaccharide produced by R.leguminosarum. Could be involved in the development of the biofilm matrix made of EPS. Secreted by the type I secretion system PrsDE. Contains two Ra/cadherin-like domains composed mostly of beta-sheets joined by a linker region. Proper folding and stability are dependent on the binding of one calcium ion per protein molecule.