Enoxacin

For most of the experiments, enoxacin (E3764, Sigma-Aldrich) was dissolved in 100% DMSO and added to the growth medium at the final concentration of 50 µM. Generally, cells were grown in the presence of 50 µM enoxacin for 48 hours, unless stated otherwise. Cells were exposed to 2 or 5 Gy of ionizing radiation with a high-voltage X-ray generator tube (Faxitron X-Ray Corporation). siRNAs for human TARBP2, PACT, TNRC6A, -B and -C, 53BP1, and GFP or non-targeting siRNAs as negative controls, were purchased from Dharmacon (Table S1) and transfected using Lipofectamine® RNAiMAX (Thermo-Fisher) at the final concentration of 20 nM. Cherry-LacR and I-SceI expressing plasmids^{33 (link)} were transfected with Lipofectamine® 2000 (Thermo-Fisher). I-SceI expression in I-HeLa111 was induced by administrating 1 µg ml⁻¹ doxycycline for 24 hours. To induce Trf2 knock-out, Trf2^F/F MEFs^{35 (link)} were incubated with 600 nM 4-hydroxytamoxifen (4OHT) for 48 hours.

All of the chemicals used in this investigation were of analytical grade. Danofloxacin (DAN), ofloxacin (OFL), levofloxacin (LEV), garenoxacin (GAR), pefloxacin (PEF), gatifloxacin (GAT), clinafloxacin (CLI), sarafloxacin (SAR), lomefloxacin (LOM), tosufloxacin (TOZ), sparfloxacin (SPA), difloxacin (DIF), pazufloxacin (PAZ), marbofloxacin (MAR), moxifloxacin (MOX), rufloxacin (RUF), norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR), pipemidic acid (PIP), nalidixic acid (NAL), oxolinic acid (OXO), orbifloxacin (ORB), enoxacin (ENO), nadifloxacin (NAD), flumequine (FLU), bovine serum albumin (BSA), ovalbumine (OVA), casein, 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS), N,N-dimethylformamide (DMF), ethylenediamine hydrochloride, triethylamine, sodium borohydride, glutardialdehyde, 4-aminomethylfluorescein (4-AMF), 3,3′,5,5′-tetramethylbenzidine (TMB), and Tween-20 were Sigma-Aldrich (St. Louis, MO, USA) products. Complete and incomplete Freund’s adjuvants were produced by Becton Dickinson (Franklin Lakes, NJ, USA). Peroxidase-labeled anti-rabbit immunoglobulins were from the Gamaleya Institute of Microbiology and Epidemiology (Moscow, Russia). All other chemicals (salts and solvents of analytical grade) were from Khimmed (Moscow, Russia).

Antibiotics (Figure 1) enrofloxacin (ENRO), norfloxacin (NOR), lomefloxacin (LOME), enoxacin (ENOX), levoxacin (LEVO), ciprofloxacin (CIPRO), methacrylic acid (MAA), 2-trifluoromethacrylic acid (TFMAA) and 2-hydroxyethyl ethylene glycol dimethacrylate (EDMA) were obtained from Sigma-Aldrich (St. Louis, MO, USA). 2,2′-azobis(2,4-dimethylvaleronitrile) (ABDV) was purchased from Wako (Neuss, Germany) and used as received. Sarafloxacin hydrochloride (SARA), was a gift from Fort Dodge veterinaria (Girona, Spain). Danofloxacin (DANO) was purchased from Riedel-de-Haën (Seelze, Germany).
Acetonitrile (ACN) and methanol (MeOH) (HPLC-grade) were provided by SDS (Peypin, France) and trifluoroacetic acid (TFA) (HPLC-grade, 99%) was from Fluka (Buchs, Switzerland).
Water was purified using a Milli-Q system (Millipore, Bedford, MA, USA). The monomers were purified, as required, by chromatography immediately before use, using an inhibitor–remover from Aldrich (Milwaukee, WI, USA). All solutions prepared for the HPLC were passed through a 0.45 µm nylon filter before use. 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES) was supplied by Aldrich (Steinheim, Germany). Trifluoroacetic acid (TFA) (HPLC-grade) was from Fluka (Buchs, Switzerland).