Fig. 2: Structures of mtSSU assembly intermediates co-isolated via MTG3FLAG.
From: Coupling of ribosome biogenesis and translation initiation in human mitochondria
a MTG3FLAG co-isolates mtSSU MRPs and several mtSSU assembly factors. FLAG-immunoprecipitation was performed with lysed mitochondria from HEK293 wild type (WT) cells and a stable HEK293 cell line inducibly expressing MTG3FLAG, and subsequently analyzed via western blotting with indicated antibodies (total = 3%, eluate = 100%). Similar results were obtained in n ≥ 3 biologically independent experiments. b Schematic depiction of the mature 12S rRNA secondary structure. Regions are depicted by their level of maturation in each state, with M corresponding to the mature mtSSU (PDB: 3J9M2;). c Cryo-EM structures of the MTG3-TFB1M-mtRBFA(in)-bound small mitoribosomal subunit (mtSSU) intermediate (state A), METTL15-mtRBFA(in)-bound mtSSU (state B), and METTL15-mtRBFA(out)-bound mtSSU (state C). The 12S rRNA (red) and indicated biogenesis factors are shown as cartoon and the remaining mitoribosomal proteins (MRPs) are indicated as white transparent surface. MTG3: light blue, TFB1M: lime green, mtRBFA: indigo, METTL15: turquoise, mS38: beige2. Close-up views of the immature decoding center (d) and of the foot region (e) in state A. Coloring as in (c), with cryo-EM densities (from map A3) of immature rRNA helices shown as red surface. Close-up views of the immature decoding center with cryo-EM densities (from maps B-C3) (f, h) and of the foot region (g, i) in state B and C, respectively. (e, g, i) Close-up views of the foot region in each state, showing the densities for MTG3 (state A, map A3), or MTG3NTD and h44 with altered trajectory (state B-C, 15 Å low-pass filtered maps B1 and C1). Mature h44 is depicted by red dashed lines and would clash with MTG3 and MTG3NTD.
