Left: schematic depicting DNA end masking and pseudo-circularization when streptavidin tetramers are added to biotinylated linear DNA. Right: cleavage assays with JET nuclease (JetABC: at 12.5 nM d-o-p, JetD dimer: at 25 nM dimer) and MR nuclease (at 125 nM, heterotetramer) on DNA species obtained by streptavidin (at 100 nM monomer conc.) incubation with single or double biotinylated 2.3 kb DNA substrates (at 7 nM). DNA species were resolved on a 1% agarose gel containing ethidium bromide (EtBr). The inset depicts the architecture of the DNA end processing nuclease E. coli Rad50/Mre11 (MR) that serves as control nuclease in this study.28,29,30,31,32,33,34,35