Fig. 3: The ribosomal RNAs of the Chlamydomonas mitoribosome are fragmented.

a Schematic representation of the entire C. reinhardtii mitochondrial genome. The protein-coding genes are displayed in gray, and the rRNA fragments incorporated in the mitoribosome are individually colored. The tRNA genes are indicated by letters. b Browser view of the RNAseq data of libraries built from purified mitochondria (blue) and purified mitoribosome (orange) fractions. Data range is [0-700], mapped to the Chlamydomonas mitochondrial genome in a. c rRNA fragment 3D organization in the LSU and the SSU. The r-proteins are shown as a gray silhouette. The fragment colors match the color code used in a. d Zoomed view of the L2a/b coverage (top). The L2b fragment is absent in the ribosomal fraction in the RNAseq analysis, which was confirmed by northern blots (bottom) and the cryo-EM reconstruction. Northern blot was performed for the L2a and L2b fragments on total cell extracts (total), mitochondrial (mito), and mitoribosomal fraction (ribo) on one biological sample. e Detailed view of the rRNA extremities of the L3b fragment and its pairing with the L2a and L4 fragments. The atomic models are shown mapped into the cryo-EM densities. f Comparison of the Chlamydomonas mitoribosome rRNAs with the E. coli ribosome. rRNA reductions are shown in blue.