| Sumario: | Ribosomal RNA is the main constituent of ribosomes, where it not only provides a structural scaffold for r-proteins but also a decoding mechanism for translation of mRNAs into proteins. Modulation of the cellular rRNA content is at the heart of the strictly regulated biosynthesis of ribosomes and allows the cells to adapt their translation machinery to environmental fluctuations. In bacteria, the genes encoding rRNA molecules are typically organised in operons. The operons encode large primary transcripts that are processed and chemically modified. The resulting rRNAs are assembled into ribosomes together with ribosomal proteins in a multi-step process. The activity of the assembled ribosome is constantly monitored, and a large set of enzymes is responsible for rRNA quality control, repair and degradation in case of ribosomal damage. The synchronisation of these processes creates an elaborate network of reactions in charge of the synthesis of the translation apparatus, its modification in response to environmental changes and its protection against stress factors. This review illustrates the current knowledge of the key events that occur in the lifecycle of rRNA molecules in bacteria and it highlights the importance of a fine regulation of rRNA content for the maintenance of ribosome homeostasis.
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