A Genetic Tool to Quantify trans-Translation Activity in Vivo

Abstract In bacteria, trans- translation is the main quality control mechanism for rescuing ribosomes arrested during translation. This key process is universally conserved and plays a critical role in the viability and virulence of many pathogens. We developed a reliable in vivo double-fluorescence reporter system for the simultaneous quantification of both trans -translation and the associated proteolysis activities in bacteria. The assay was validated using mutant bacteria lacking tmRNA, SmpB, and the ClpP protease. Both antisense tmRNA-binding RNA and a peptide mimicking the SmpB C-terminal tail proved to be potent inhibitors of trans -translation in vivo . The double-fluorescent reporter was also tested with KKL-35, an oxadiazole derivative that is supposed to be a promising trans -translation inhibitor, and it surprisingly turns out that trans -translation is not the only target of KKL-35 in vivo .