A Quantitative, Genome-Wide Study of Translation Efficiency in E. coli

There has been much interest in how living cells control protein synthesis, both at the single-gene and genome-wide levels. Here we present a comprehensive study of translation in E. coli, combining quantitative proteomic and transcriptomic methods in a wide variety of growth conditions. We find that most mRNAs are transcribed with similarly high efficiencies across the growth conditions examined. The high average efficiency corresponds to a high density of translating ribosomes on the mRNAs, about 8 Rb/kb, not far from the range of maximal packing. Variations in translation efficiencies, due e.g. to post-transcriptional regulation, are negligible for most genes. A simple model of translation initiation is introduced to discuss the coordination between translation initiation and elongation processes, and to explore what may be optimal for protein synthesis in E. coli.