Fig. 6: Tma20 and Tma22 are responsible for the majority of 40S recycling at stop codons.

a Average 80S (top) and 40S (bottom) ribosome footprint occupancy across all genes aligned at their stop codons for the tma20∆ (left), tma22∆ (middle), and tma64∆ (right) strains. The data reveal a queued 80S peak one footprint length behind the stop codon (top) and increased 40S peak on the stop codon (bottom) in the tma20∆ and tma22∆ strains. These trends are much smaller in the tma64∆ strain. Footprints plotted by 5′ ends. b Analysis of 40S stop codon peak heights (total count of footprints at the stop codon) showing a strong increase in stop codon peak height in the tma20∆ and tma22∆ strains (dots above the diagonal) but only a small shift in the tma64∆ strain, compared to WT. The lack of outliers indicates the step in 40S recycling slowed by loss of the Tma proteins is also slow in WT cells. Each point represents the data for one gene. Footprint reads were quantitated by shifting them by 14 nt and then counting reads around the stop codon. c Ratio of 80S footprint density in 3′UTRs to their respective ORFs is plotted for the individual tma deletion vs WT cells. Each point represents the data for one gene. The data are consistent with increased 3′UTR 80S ribosome occupancy for most genes in the tma20∆ and tma22∆ strains (most dots are above the diagonal) but only a small shift in the tma64∆ strain, compared to WT. d Average fraction of 80S ribosome occupancy in a window surrounding 3′UTR AUG codons (in all frames) normalized to ORF ribosome density level. e Average 40S ribosome occupancy in a window surrounding 3′UTR AUG codons. A peak above background level is evident for the tma20∆ and tma22∆ strains on AUG codons, consistent with the mechanism of 40S reinitiation. nt nucleotide, rpm reads per million, ORF open reading frame. Source data are provided as a Source Data file. See also Supplementary Fig. 5.