Culture Conditions Affect Differently the Translation of Individual Escherichia Coli mRNAs

Abstract

Individual bacterial mRNAs are translated at very different rates (Ray and Pearson, 1975; McCarthy, et al., 1985). Extensive work during the last decade has revealed that these unequal performances largely stem from sequence differences in the region contacted by the ribosome during initiation (Ribosome Binding Site or RBS: see Steitz, 1969). Thus, the nature of the initiation codon, the length of the Shine-Dalgarno sequence (SD), and the spacing between them, all contribute to the translational efficiency (Gold, 1988). Additional RBS sequence elements, less characterized to date, are probably also important (McCarthy et al., 1985; Petersen et al., 1988). Finally, the extent of secondary structure around RBSs profoundly affects their efficiencies (Gold, 1988; de Smit and van Duin, 1990). However, the role of these different elements has not been investigated as a function of growth conditions. The concentration of ribosomes, factors, precursors, etc, vary according to the metabolic state of the cell (Bremer and Dennis, 1987), and in vivo such changes affect differently the translational yields from individual mRNAs (Gualerzi et al., 1988). Should this also occur in vivo, then the translational yields from individual mRNAs would be expected to change according to growth conditions.