Fig. 5: Impact of translation on downstream cassette expression.
From: The expression of integron arrays is shaped by the translation rate of cassettes
a Translation initiation rates of cassettes were predicted using the web tool RBS Calculator 2.1. Correlations between gfp mRNA levels of all ARCs and their translation initiation rates (TI); codon adaptation index (CAI) and minimum fold energy of mRNA. Correlations between the GC content of all ARCs and their gfp mRNA levels and predicted TI. Spearman’s rank correlation coefficient (ρ) and p-values are indicated. b GFP fluorescence and gfp mRNA levels (fold change) of a subset of ARCs and their respective translation mutants. met::stop represents the indicated ARC with the methionine initiation codon replaced by a stop codon. 50%::stop represents the indicated ARC with a stop codon introduced at the 50% of the CDS. Bars represent the mean and SD of at least n = 3 biological replicates. Statistical significance was assessed with one-way ANOVA followed by Dunnett’s multiple comparison test fluorescence levels of each ARC and their respective mutants (see Supplementary Fig. 8) ns, not significant; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. c Schematic representation of mutants used to study the impact of translation on polar effects in ARCs. Correlation between the length of the untranslated segment and the respective decrease in GFP fluorescence. r indicates the Spearman’s correlation coefficient. d Effect of subinhibitory doses of chloramphenicol on downstream cassette expression. For each indicated strain the left panels display the GFP/OD, with line and shading representing the mean and SD of three biological replicates, respectively. The right panels display the area under the curve (AUC) of the Cm-treated cultures over the non-treated control with bars representing the mean and SD of n = 3 biological replicates. A two-sided one-sample t-test was performed to determine whether mRNA fold changes (b) or AUC ratios (d) are significantly different from 1. ns not significant; *p < 0.05; ***p < 0.001; ****p < 0.0001. Source data are provided as a Source Data file.
