Single-molecule imaging with a tagged ribosome to explore trans-translation.

Single-molecule imaging is a powerful technique to visualize molecular interactions and movements. Translation is one of the most interesting targets for researchers with the molecular-imaging skills, since mRNA, tRNA and translation factors interact with or move inside or on the ribosome in an ordered manner. Trans-translation is a bacterial quality control system to rescue the ribosomes stalled at the 3' end of the mRNA, and this phenomenon is recapitulated in vitro with defined factors including two trans-translation-specific entities tmRNA and SmpB. Zhou et al. (Single molecule imaging of the trans-translation entry process via anchoring of the tagged ribosome. J Biochem 2011;149:609-618.) successfully visualized the interaction of the tmRNA-SmpB complex with the ribosome by immobilizing the ribosome on the quartz surface with the HaloTag technology. This ribosome-anchoring system may be useful for the imaging analysis of other processes of translation.