title: GSM7596210: SIMM057_2; Homo sapiens; OTHER
library_construction_protocol: MitoIP-Ribo-Seq, MitoIP-Thor-Ribo-Seq, and MitoIP-Thor-Disome-Seq: Cells were cultured in 15-cm dishes, washed with ice-cold PBS, and lysed with 1200 µl of hypotonic buffer (10 mM HEPES-KOH pH 7.5, 10 mM KCl, 1.5 mM MgCl2, 1 mM DTT, 100 µg/ml cycloheximide, and 100 µg/ml chloramphenicol). The lysate was incubated with anti-TOM22 antibody-conjugated beads from Mitochondria Isolation Kit, Human (Miltenyi Biotec) for 60 min at 4°C. The subsequent wash and elution steps were performed with wash buffer (10 mM HEPES-KOH pH 7.5, 10 mM KCl, 15 mM MgCl2, 1 mM DTT, 100 µg/ml cycloheximide, and 100 µg/ml chloramphenicol), according to the manufacturer's instructions. The eluted mitochondrial fraction was pelleted by centrifugation at 7,000 × g for 10 min at 4°C and resuspended in modified lysis buffer (20 mM Tris-HCl, pH 7.5, 150 mM NaCl, 15 mM MgCl2, 1 mM DTT, 1% Triton X-100, 100 µg/ml cycloheximide, 100 µg/ml chloramphenicol, and 2.5 U/ml TURBO DNase). After clarification by centrifugation at 20,000 × g for 10 min at 4°C, the supernatant was used for library preparation. For the mitoribosome run-off assay, HEK293 cells were pre-treated with 100 µg/ml retapamulin for 30, 60, 90, 120 s, or 30 min and then incubated with 100 µg/ml chloramphenicol and 100 µg/ml cycloheximide to arrest translation elongation. Subsequently, cell lysis and mitochondrial purification were performed as described above, adding 100 µg/ml retapamulin to all the solutions. For the mouse cardiac muscle, the frozen tissues were pulverized with 600 µl of liquid nitrogen-frozen hypotonic buffer using the Multi-beads Shocker at 3000 rpm for 30 sec for 2 cycles (Yasui Kikai). The lysate was clarified by an EASYstrainer (Greiner Bio-One), and mitochondria isolation was conducted as described above. Ribo-Seq and RNA-Seq: Cells in a 10-cm dish were lysed with 600 µl of lysis buffer (20 mM Tris-HCl pH 7.5, 150 mM NaCl, 5 mM MgCl2, 1% Triton X-100, 1 mM DTT, 100 µg/ml cycloheximide, and 100 µg/ml chloramphenicol) and treated with 25 U/ml TURBO DNase (Thermo Fisher Scientific). Then, the lysate was clarified by centrifugation at 20,000 × g for 10 min at 4°C. Ribo-seq and MitoIP-Ribo-Seq: RNase treatment, ribosome pelleting, Ribo-FilterOut, size selection, preadenylated linker ligation, rRNA depletion, reverse transcription, cDNA circularization, and PCR amplification. MitoIP-Thor-Ribo-Seq and MitoIP-Thor-Disome-Seq: preadenylated linkers with the antisense sequence of T7 promoter were ligated and footprints were amplified by in vitro transcription. RNA-seq: the libraries were prepared by a SEQuoia Express Standard RNA Library Prep Kit (Bio-Rad).