FIG. 9.

Expression properties of TadA-T7 lysine (K210) mutants. (A) A. actinomycetemcomitans tadA mutant strains (AA1360) expressing wild-type TadA-T7, TadA-T7(K210A), or TadA-T7(K210Q) were grown for ∼24 h in the presence 0, 0.01, or 0.1 mM IPTG. Top, Coomassie blue-stained gel (12% polyacrylamide) to demonstrate total amount of protein loaded; bottom, Western blot analysis with anti-T7-TAG antibody to detect TadA-T7. (B) Failure of TadA-T7(K210A) and -K210Q mutant polypeptides to bind to the T7-TAG affinity column. Extracts from E. coli expressing either TadA-T7(K210A) or TadA-T7(K210Q) were passed over affinity columns as described in Materials and Methods. Approximately equal amounts of protein were detected in both the input and flowthrough fractions.