Translational Regulation of Ribosomal Proteins in Escherichia coli

摘要: In 1979–1980, a number of papers appeared that suggested control ribosomal (r)-protein synthesis in Escherichia coli takes place at the translational level. Gene-dosage experiments, for instance, showed messenger RNA (mRNA) rates increase with extra copies an r-protein operon, but rate changes very little.1–3 Overproduction specific r-proteins vivo repressed other same operon,4 and effect was observed when purified were added to vitro translation systems.5–7 These experiments demonstrated some act as autogenous, repressors negative feedback mechanism adjusts match (rRNA) (see Fig. 1). detail, autoregulation hypothesis proposes (1) each r- protein operon codes one repressor; (2) repressor is able bind specifically rRNA single mRNA target site; (3) binding site affects all downstream cistrons (i.e., ribosomes do not load independent sites, only regulated entry site); (4) significant free accumulates binds available assembled into ribosomes. There evidence most E. operons, though mechanisms may contribute operons (e.g., transcription attenuation S10 operon).8 Excellent reviews summarizing this regulatory scheme evaluating its importance regulation ribosome biosynthesis have appeared.9,10