A review of Shi et al. Pyrazinamide inhibits trans-translation in Mycobacterium tuberculosis. Science (2011) vol. 333 (6049) pp. 1630-2
This study was recently published in the prestigious journal Science attempted to explain the mode of action for an important antibiotic, Pyrazinamide, used in treating tuberculosis. Due both to the high profile of this work, and the conclusion they draw regarding trans-translation, I will provide below a review of this article.
The interested reader should be aware of one important fact when approaching this article: there are different versions of it, depending on how you access it. The open access version at Pubmed is outdated; a more recent version (with updated Figure 3) is available from the journal Science itself.
- Demonstrates binding of ribosomal protein S1 to POA (active form of Pyrazinamide drug)
- Suggests mechanism of action for POA: binding to S1 inhibits trans-translation.
- Quality of trans-translation related data (western blots) make the conclusion drawn by the authors questionable.
- Alternative explanations to trans-translation rescue of stalled ribosomes in their in vitro system are not ruled out, undermining the conclusions drawn.
In this study, Shi and colleagues sought to identify the target and antibiotic mechanism of the anti-tuberculosis drug Pyrazinamide. This drug is important in treatment of tuberculosis, particularly in clearing persister cells through combination with other compounds. In order to accomplish this task, the authors used affinity chromatography to capture M. tuberculosis proteins that are capable of interacting with the drug. Through this approach, ribosomal protein S1 is identified as the primary target.
Using ribosomal protein S1 (RpsA) as a lead, the authors attempt to explain the mode of action for PZA. Binding studies using isothermal titration demonstrate more conclusively that PZA is capable of binding RpsA Furthermore, a PZA resistant strain with mutant RpsA genes that cannot bind the drug is identified. Finally, the authors use an in vitro translation system to assess the effect of PZA on translation and trans-translation. The conclusion drawn from these studies is that PZA specifically inhibits trans-translation, but only in the context of M. tuberculosis ribosomes.