library_construction_protocol: Cell pellets were lysed on ice using lysis buffer (20 mM Tris-HCl pH 7.4, 100 mM NaCl, 5 mM MgCl2, 1% Triton X-100, 1 mM DTT, 20 U ml-1 RQ1 DNAse (Promega, M6101), 0.1% NP-40, 100 µg mL-1 cycloheximide) and triturated through a 21-gauge needle five times. Preparation of RIBO-seq libraries was carried out by TB-SEQ, Inc. Lysates were digested with RNase I for 45 min at room temp. Digestion was stopped with SuperaseIN and monosomes purified by size exclusion chromatography on MicroSpin S-400 HR columns (GE Healthcare). Size selection of footprints with length 25-33 nt was performed by electrophoresis on 15% TBE-urea gels. Illumina ready RIBO-seq libraries were prepared using a SMARTer smRNA-seq kit (TakaraBio). Library concentrations were measured by qubit fluorometer and their quality assessed on an Agilent 2100 bioanalyzer. RIBO-seq libraries were sequenced on an Illumina Novaseq 6000 sequencer, single read, 1x50 cycles. Preparation of matching RNA-seq libraries was carried out by TB-SEQ, Inc. Total RNA was purified from an aliquot of cell lysate and polyA mRNA prepared using a NEBNext polyA mRNA magnetic isolation module following manufacturer instructions. mRNA fragmentation was conducted for 20 min at 94°C  to generate RNA fragments of sizes similar to those of the ribosome footprints. SMARTer smRNA-seq kit (TakaraBio) was used to generate Illumina ready RNA-seq libraries. Library concentrations were measured by qubit fluorometer and their quality assessed on an Agilent 2100 bioanalyzer. RNA-seq libraries were sequenced on an Illumina Novaseq 6000 sequencer, single read, 1x50 cycles.