RIBOSOME, RIBOSOME STRUCTURE, PROTEIN-RNA COMPLEX, RIBONUCLEOPROTEIN, RIBOSOMAL PROTEIN, RNA-BINDING, RRNA-BINDING, ANTIBIOTIC RESISTANCE, REPRESSOR, TRANSCRIPTION, TRANSCRIPTION REGULATION, TRANSCRIPTION TERMINATION, TRANSLATION REGULATION, ACETYLATION, TRNA-BINDING, METHYLATION, ENDONUCLEASE, HYDROLASE, NUCLEASE 3I21 CRYSTAL STRUCTURE OF THE E. COLI 70S RIBOSOME IN AN INTERMEDIATE STATE OF RATCHETING