Figure 6

The weakening stress response during aging is mainly driven by decline of protein translation efficiency. (a) Design and characterization of the Tps2-PP7-PCP system. Schematic depicting the multiple stem-loop sequences (PP7) used to tag Tps2, and RNAs are visualized by the recruitment of iRFP-labeled PCPs. (b) Target protein and depiction of transcriptional bursting. Image of live cells coexpressing Tps2-GFP and RNA-iRFP. (c) Appearance of Tps2 transcription site signals at the indicated times. White arrowheads denote transcription sites. (d) Transcriptional response to a sequence of stimulation pulses (six typical cells). Different colors represent different single cells. The inset is stress response patterns of RNA at different times during the aging process of one representative single cell. The shade represents the duration of stimulus application (left). Integral of mRNA calculated from six cell traces showed that the production of mRNA can maintain an almost stable value during the aging process (right). (e) (left) The change in the parameters during the cellular aging process and curve fitting. A linear function was used to fit k₂, and a Hill function was used to fit d₂. (right) Comparison of model fits to the experimental data sets for periodic 0.4 M KCl in budding yeast. The solid red and blue curves represent the theoretical and experimental results, respectively, and the vertical dashed lines indicate the start and end of the stimuli.