Effects of MtbTopA on mRNA cleavage activities of Rv1495. (A) mRNA cleavage experiments were performed as described under ‘Materials and Methods’ section. A variant concentration of Rv1495 (0.5–2.0 μM) or MtbTopA (40–120 nM) proteins was incubated with 0.5 μM mRNA substrates in the reactions. The mRNA substrate, products and their sequences were indicated by arrows. Rv0054 was used a negative control. (B) Two mutant proteins of MtbTopA and their interactions with Rv1495. The names given to mutants (NTD and CTD) and their amino acid regions are indicated. Bacterial two-hybrid assays for all mutants were performed as described under ‘Materials and Methods’ section. + represents growth on the screening plate; − represents no growth on the screening plate. (C) Effects of N-terminal and C-terminal mutant proteins of MtbTopA on the mRNA cleavage activities of Rv1495. The protein concentrations were indicated on top of the panel.