Secondary structure representations of segments srRNA-II and srRNA-IV from T. brucei and segments LSU-10, LSU-13, and LSU-14 from E. gracilis. These structures were created using the S. cerevisiae LSU secondary structure as a guide (Petrov et al. 2014); S. cerevisiae numbering system is used accordingly. Structural alignments of T. brucei and E. gracilis small segments over the S. cerevisiae LSU crystallographic structure guided their creation (PDBID 4V88) (Supplemental Tables S17, S18; Ben-Shem et al. 2011). Ribonucleotides within regions of interaction are marked with solid filled circles and a region number in the same color. Missing residues and regions were not mapped due to a lack of structural counterpart in S. cerevisiae. (A) Secondary structure of T. brucei segment srRNA-II (cyan), where interacting regions 3–13 have been mapped. These regions are a common feature among all ribosome structures (Table 1). (B) Secondary structure of T. brucei segment srRNA-IV (purple). Regions 1, 3, 5, 6, and 7 from srRNA-IV are a common feature among segmented and unsegmented ribosomal structures (Table 2). (C) Secondary structure of E. gracilis segment LSU-10 (green), where interacting regions 3–12 have been mapped. Regions 3–13 are a common feature among all ribosomes (Table 1). (D) Secondary structure of E. gracilis segments LSU-13 (dark blue) and LSU-14 (light brown). Interacting regions 1, 3, 5, 6, and 7 are a common feature among segmented and unsegmented ribosomes (Table 2).
