tRNA/mRNA Mimicry by tmRNA and SmpB in Trans-Translation
Figure 3
Molecular mimicry of tRNA and mRNA from directed hydroxyl radical probing. (a) Location of TLD-SmpB (left) and tRNA (right) in the ribosomal A-site from directed hydroxyl radical probing [48, 49]. The N-terminal globular domain of SmpB mimics the lower half of tRNA in the A-site. The tertiary structures of TLD-SmpB from T. thermophilus [50] and 70S ribosome from E. coli [51] were used. (b) Location of the C-terminal tail of SmpB from directed hydroxyl radical probing. Cleavage sites by Fe(II)-tethered A-site and P-site SmpB are colored yellow and green, respectively. The C-terminal tails are located on the mRNA path, suggesting that the C-terminal tail of SmpB mimics mRNA in both the A-site and P-site. P-site SmpB and mRNA are colored red and pink, respectively. The tertiary structure model of 70S ribosome from T. thermophilus [52] is used.
