Fig. 4
From: Numerous cultivated and uncultivated viruses encode ribosomal proteins
Ribosome analysis of extracts from NM522 Escherichia coli cells. a Sedimentation profiles of NM522 E. coli ribosomes. Wild-type NM522 E. coli cells (black curve) and cells expressing viral bS21 (red), bL12 (green) or HPF (blue) were lysed and their ribosomes were purified using a 10–50% sucrose gradient (see experimental section). The dotted lines indicate the fractions that were pooled and further analyzed by mass spectrometry. b Quantification of in vitro translation of GFP by E. coli 70S ribosomes carrying either E. coli wt bS21 (control), E. coli streptavidin-tagged bS21 (70S-eS21) or viral streptavidin-tagged bS21 (70S-pS21). Translation assay was performed using PURExpress® ΔRibosome Kit, complemented with 10 pmol of purified ribosomes and 250 ng of a PCR product encoding for GFP under control of T7 promoter. Fluorescence signal was detected by spectrofluorimetry at 510 nm with an excitation at 485 nm. The percentage of fluorescence was measured with respect to the translation control. The error bar represents the standard deviation measured over three independent experiments. The variance was analyzed using Kruskal–Wallis test followed by a Dunn’s multiple comparison test (p-value for 70S-pS21 = 0.0219)
