FIG. 7.

rHtrA degrades rTRP120 and native TRP120. (A) Surface expression of HtrA on a representative bacterium. Host cell-free bacteria (Ec) were stained with rabbit anti-HtrA (HtrA) or preimmune serum (pre), followed by Alexa Fluor 555-conjugated anti-rabbit IgG and dog anti-E. chaffeensis, followed by FITC-conjugated anti-dog IgG. The antibody dilution was 1:100. The right panels are merged images. Scale bar = 2 μm. (B) rHtrA (1 μg) was incubated with 5 μg E. chaffeensis membrane fraction (TRP120) or 1 μg rTRP120 for 12 h at room temperature in the presence or absence of 10 mM DFP. (C) Anti-HtrA (αHtrA) IgG inhibits rTRP120 degradation by rHtrA. rTRP120 (1 μg) was incubated with rHtrA (1 μg) in the presence of anti-HtrA IgG (5 μg) or preimmune IgG (5 μg) for 5 h at room temperature. (D) Anti-HtrA inhibits CDGA-induced degradation of TRP120. Host cell-free bacteria isolated from 10⁶ infected cells were incubated with 0.3 mM CDGA in the presence of anti-HtrA IgG (5 μg) or preimmune IgG (5 μg) or with solvent (1% [vol/vol] DMSO) alone. TRP120 was detected by Western blotting. The relative densities of rTRP120 or native TRP120 bands observed following different treatments are shown below each lane.