FIG 3.

The ω loop is required for the assembly of M. tuberculosis core. (A) Sequence alignment of the R2 region in ω subunits from M. tuberculosis, E. coli, and T. thermophilus. The ω loop region is marked with a dashed box. The amino acid numbering in top part is for M. tuberculosis ω. (B) Structural overlay of the ω R2 regions in M. tuberculosis (aa 35 to 104, yellow, PDB 5UH8), E. coli (aa 1 to 59, blue, PDB 4YG2), and T. thermophilus (aa 1 to 73, orange, PD 1IW7). (C) Purified M. tuberculosis core with a mutated ω subunit carrying the loop regions from E. coli (aa 31 to 44) or T. thermophilus (aa 31 to 58) (ω^E-loop and ω^T-loop, respectively). (D) In vitro abortive transcription of purified M. tuberculosis coreΔω derivatives at Rv1494p. RbpA and σ^A were added in each reaction. Mtb, M. tuberculosis; Eco, E. coli; Tth, T. thermophilus.