Accessibility of CFH/FHL-1 binding proteins of B. garinii ST4 PBi by different proteases. Spirochetes of B. garinii ST4 PBi were incubated with either proteinase K or trypsin at concentrations of 12.5 to 100 μg/ml or in buffer without any protease (0). After 1 h of incubation, cells were lysed by sonication as described in Materials and Methods. Each protein lysate was then subjected to 10% Tris/Tricine SDS-PAGE, blotted to membranes, and analyzed by Western or ligand affinity blotting. CFH/FHL-1 binding proteins were identified using NHS and a polyclonal anti-CFH antibody. Equal sample loading was assessed by detection of flagellin (FlaB) using MAb L41 1C11 1C11 at a dilution of 1:1000. Mobilities of molecular mass standards are indicated to the left. Four proteins able to bind CFH/FHL-1 and they are readily digested by proteinases and therefore located on the membrane.