G box

Western blots were performed as described earlier [54] (link). The membranes were incubated with primary antibodies directed against RED or SMU1 (Santa Cruz), A/PR/8/34 virions [55] (link), NS1 (kindly provided by Daniel Marc, INRA-Tours, France), NS2 (kindly provided by Florence Baudin, EMBL-Heidelberg, Germany), M1 (clone GA2B, Pierce), M2 (clone 14C2, Pierce), GAPDH (Pierce), tubulin (Calbiochem), the HA tag (clone 16B12, Covance), the Gaussia luciferase (New England Biolabs), with peroxidase-conjugated Streptavidin (IBA) and peroxidase-conjugated secondary antibodies (GE Healthcare), and with the ECL 2 substrate (Pierce). The membranes were scanned in a G-Box (Syngene), the chemiluminescence was acquired and quantified with the GeneSnap and GeneTools softwares (SynGene), respectively.

All DNA oligonucleotides were purchased from Invitrogen (Thermo Fisher Scientific). Their sequences are listed in Table S1, Supporting Information. All the strands were diluted to 100 µm in TE buffer (10 mmol L⁻¹ Tris‐HCl, 1 mmol L⁻¹ EDTA, pH 8.0) and quantified by UV before stored at −20 °C. Seven DNA oligonucleotides were equimolarly mixed together in TM buffer (20mm  Tris, 50mm  MgCl₂, pH 8.0) at final concentration of 1 µm. The mixture was heated at 95 °C  for 5 min, then quickly cooled to 4 °C and maintained for 5 min. The formed DNA tetrahedrons were stored at 4 °C before use. Agarose gel electrophoresis was implemented to confirm the assembly of the DNA tetrahedron. 3% agarose gels were prepared in 1× TBE buffer (89 mmol L⁻¹ Tris‐boric, 2 mmol L⁻¹ EDTA, pH 8.0) supplemented with YeaRed Nucleic Acid Gel Stain (Yeasen). DNA Samples (10 µL, 1 µm) were mixed with 2 µL 6× loading buffer (Yeasen), run at 100 V for 60 min in 1× TBE, and imaged using a G:Box (Syngene). For AFM imaging of the DNA tetrahedron, fresh mica surface was first incubated with a 2.5 nm solution of the TDN for 5 min. Then, the sample solution was washed off by TM buffer. Finally, 50 µL of the TM buffer was added to the mica surface and AFM imaging was performed under the liquid phase model with a Dimension FastScan (Bruker Santa Barbara, US) and SNL‐10 probes.

For protein extraction, lysis was performed with our standard lysis buffer (50 mM Tris, 25 mM β-glycerophosphate, 50 mM NaCl, 1 mM EDTA, 1 mM EGTA, 0.5% (v/v) Triton X100, 1 mM DTT, 1 mM benzamidine, protease and phosphatase inhibitor cocktail (Sigma). SDS-PAGE was performed as previously described12 (link). The total protein concentrations were determined using a standard Bradford protein assay. Proteins were transferred onto PVDF membrane which was then blocked in Tris-Buffered Saline (TBS) containing 0.1% Tween20 and 5% (w/v) non-fat dry milk powder for 1 h at room temperature. The membrane was incubated with primary antibody overnight at 4 °C in TBS; 0.1% Tween20, 5% (w/v) non-fat dry milk or 5% (w/v) bovine serum albumin (BSA). Antibodies were diluted according to the manufacturer’s instructions. Membranes were washed 4 times for 5 min in TBS, 0.1% Tween20. Secondary antibodies coupled to HRP, diluted at 1/5000 in TBS, 0.1% Tween20, 5% (w/v) non-fat dried milk, was incubated at room temperature for 1 h. Membranes were washed 4 times for 5 min in TBS, 0.1% Tween20. A final wash of 5 min was performed in TBS. Luminata western HRP substrate (Millipore) and a chemiluminescence imager (G:box, Syngene) were used to detect the signals.

E. coli in the logarithmic growth phase was centrifuged at 6,000 g and room temperature to collect the bacterial cells. The E. coli genomic DNA was extracted according to the Ezup Column Bacteria Genomic DNA Purification Kit instructions, and the DNA concentration was determined using an ultra-micro spectrophotometer (NanoDrop 2000, Thermo Scientific, USA). Seven samples with final DNA concentration of 25 ng/µL in 20 µL system were then prepared according to a mass ratio of LL-1 to E. coli DNA of 0, 0.25, 0.5, 1, 2.5, 5 and 10, respectively. The samples were gently inverted to allow mixing and then placed in a constant temperature water bath at 37℃ for 30 min. The mixed solution was analysed by nucleic acid gel electrophoresis and observed using a nucleic acid gel imager (G:BOX, Syngene, UK).