The distinct translational landscapes of Gram-positive and Gram-negative bacteria

Abstract

AbstractTranslational control in pathogenic bacteria is fundamental to gene expression and affects virulence and other infection phenotypes. We used an enhanced ribosome profiling protocol coupled with parallel transcriptomics to capture accurately the global translatome of two evolutionarily distant pathogenic bacteria – the Gram-negative bacteriumSalmonellaand the Gram positive bacteriumListeriaWe find that the two bacteria use different mechanisms to translationally regulate protein synthesis. InSalmonella,in addition to the expected correlation between translational efficiency andcis-regulatory features such as Shine-Dalgarno (SD) strength and RNA secondary structure around the initiation codon, our data reveal an effect of the 2ndand 3rdcodons, where the presence of tandem lysine codons (AAA-AAA) enhances translation in bothSalmonellaandE. coli. Strikingly, none of these features are seen in efficiently translatedListeriatranscripts. Instead, approximately 15% of efficiently translatedListeriagenes exhibit 70S footprints seven nt upstream of the authentic start codon, suggesting that these genes may be subject to a novel translational initiation mechanism. Our results show that SD strength is not a direct hallmark of translational efficiency in all bacteria. Instead,Listeriahas evolved additional mechanisms to control gene expression level that are distinct from those utilised bySalmonellaandE. coli.‘For the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising ’