Extended Data Fig. 4: Topoisomerase impact on the transcription unit folding.
a, Hi-C contact map magnifications (bin: 500 bp) of an E. coli strain carrying endogenous promoters facing the origin of replication. From top to bottom: without any additional promoter; with two pompA promoters; with two prpsM promoters. b, Analysis of TopA overexpression. Left panel, measurement of TopA amount by western blot in RSGB834 pBAD24 and RSGB834 pBAD24-TopA with an anti TopA antibody (gift from Dr. Yuk-Ching Tse-Dinh). Quantification of the western-blot showed a 38 fold overexpression of TopA after 2h of arabinose induction. This experiment was representative of 3 replicates. Right panel, microscopy imaging of the arabinose treated cell. The cells were fixed 2h after arabinose induction and stained with DAPI. Bacteria length and DAPI amount per cell surface was measured with a custom macro of the Omnipose software. The significance of the two-tailed Mann-Whithney test between average of both conditions is indicated by ns (not significant) or stars (*: <0.032; **: <0.0021; ***: <0.0002; ****: <0.0001). c, Hi-C contact map magnifications of the T7 system while interfering with the topoisomerases activity; contact map binned at 1kb. top; wt system with 2h arabinose treatment. Middle left; overexpression of the topA, right; gyrase inhibition using a 10 min novobiocin treatment. Bottom; log2 ratio of the interfered over the wild type; 2 kb binned. On the left same with 10 min rifampicin treatment.
