Fig. 2: Tab blocks phage tail assembly.
From: Anti-phage defence through inhibition of virion assembly
a–d Representative negatively stained transmission electron micrographs of phage particles and intermediates produced by DMS3 prophage induction in the absence (a) and presence (b) of Tab. Induction of DMS3 prophages containing the (c) tail tube (ΔTT), and (d) small terminase (ΔST) single gene deletions. Data are representative of three independent biological replicates. e Scatter plot of capsid area (nm2) for the DMS3 prophages described in panels (a–d) (n = 135 for each sample). The horizonal black line indicates the mean for each sample, and error bars indicate standard deviation. Statistical significance was measured using one-way ANOVA coupled with Dunnett’s multiple comparison test using DMS3 with Tab as reference. Adjusted p-values are reported above the graph (not significant (ns), and ****p < 0.0001). p-values = 0.0838 (DMS3 + Tab vs. DMS3; ns), 0.3030 (DMS3 + Tab vs. DMS3 (ΔTT); ns), and « 0.0001 (DMS3 + Tab vs. DMS3 (ΔST)) (f) RT-qPCR analysis of early- (A) and late-expressed (39 and 42) DMS3vir genes in the presence and absence of Tab. Bars indicate averaged relative gene expression (log10) normalized to rpoD copy number for two biological replicates. g Phage plating assay of DMS36HisTT in the presence of Tab. Data are representative of three biological replicates. h Western blot analysis of 6-His-tagged tail tube production during infection in the presence and absence of Tab (upper panel) and the corresponding 2,2,2-Trichloroethanol (TCE) stained gel showing total protein load (lower panel). Data shown are representative of three biological replicates. Time P.I., time post-infection. i Cell survival assay (colony forming units; CFU mL−1) in cells expressing Tab that were infected by DMS3vir or CRISPR-sensitive DMS3m at an MOI of 10. Uninfected cells are shown as a control. Bars represent mean values, with the error bars representing the standard deviation (n = 3 biologically independent samples). Asterisks show statistically significant differences relative to uninfected cells. *p-value < 0.05 (Paired t-test). p-values = 0.0171 for PA14, 0.0226 for PA14 (Tab), and 0.3035 for PA14 with DMS3m. j DMS3vir phage production in the absence or presence of Tab. Data are representative of three biological replicates. k Growth curves of PA14 with and without Tab and when challenged with DMS3 at an MOI of 10. Data are presented as mean values with shaded areas representing the standard deviation (n = 3 biologically independent samples). Source data are provided for panels (e, f, h, I, k).
