Binding of M. tuberculosis Ag85 to elastin and tropoelastin.
A, comparison of the elastin-binding affinities of M. tuberculosis Ag85A, Ag85B, and Ag85C. His-tagged M. tuberculosis Ag85 proteins (0.2 μm) were added to microtiter plate wells coated with 1 μg of elastin (extracted from human aorta). Bound proteins were detected by ELISA. B, binding of M. tuberculosis Ag85B to native Fn, elastin, or tropoelastin. M. tuberculosis Ag85B (0.2 μm) was added to wells coated with 1 μg of Fn (extracted from human plasma, serving as a positive control), elastins (extracted from human aorta, lung, and skin, respectively), tropoelastin (extracted from chicken aorta), or BSA (negative control). C, SPR analysis of recombinant GST-tagged human tropoelastin (full-length) interacting with immobilized M. tuberculosis Ag85B. The measured kon, koff, and KD values were 5.8 × 104 ± 0.7 m−1 s−1, 7.7 × 10−3 ± 0.5 s−1, and 0.13 ± 0.006 μm, respectively. RU, response units.