Coordinated translation initiation determines ‐1 programmed ribosomal frameshifting efficiency of chromosomal genes to impact on cell fitness

The conserved ‐1 programmed ribosomal frameshifting (‐1PRF), essential for eubacteria and RNA viruses, is thought to be exclusively regulated during translation elongation. One of the two required ‐1PRF cis ‐acting elements is a frameshifting stimulatory element (FSE), which pauses the elongating ribosome to stimulate ‐1PRF and is consecutively deformed. Consequently, the remaining hypothesis involves the coordination between translation initiation and FSE reformation, which facilitates the ‐1PRF events in trailing ribosomes. Here, we create a system that allows a tunable translation initiation rate based on the MS2 bacteriophage coat protein translation initiation hairpin to assess this conjecture. We discovered a conserved negative correlation between translation initiation rate and ‐1PRF efficiency in eubacteria and mammalian cells. Mechanistic exploration using Escherichia coli ( E. coli ) shows that a higher initiation rate reduces the frequencies of FSE reformation, resulting in lower ‐1PRF efficiency. The role of translation initiation‐mediated ‐1PRF was examined in an E. coli cellular copA/copA(Z) ‐1PRF event. The results showed that a higher translation initiation rate leads to lower ‐1PRF efficiency, sensitizing E. coli to copper stress. Together, these results suggest that translation initiation is an additional mechanism to regulate ‐1PRF to coordinate optimal protein synthesis for cell fitness, further providing the basis to investigate the interplay between translation initiation and elongation.