Figure 3.

FHmoss displays cofactor and decay acceleration activity. (A) FHmoss has complement cofactor activity. C3b (2 μg), FI (500 ng), and increasing concentrations of FHmoss or FHplasma were incubated, and C3b cleavage was visualized by SDS-PAGE and Coomassie staining. FHmoss shows similar cofactor activity compared with FHplasma as shown by a reduced intensity of the α′-chain and the appearance of the α′-chain cleavage fragments α′68, α′46, and α′43. Controls were performed without C3b, FI, or FH or with the extract of the parental moss strain Δxt/ft. (B) FHmoss efficiently promotes C3 convertase decay. FHmoss or FHplasma in indicated amounts was added to preformed C3 convertase (C3bBb) complexes (FB/factor D), and dissociation of these complexes was determined by measuring the relative amount of FB. OD at 450 nm values of control wells (without FH) were set to 100% intact C3bBb complexes. Negative control was performed without adding factor D. Data represent mean values ±SD from n=3 experiments.