Shown that constructing tST-DNA hybrids is straightforward using PCR amplification, making our method suitable for broad applications. For single molecule studies, the presented approach could be applied in combination with other peptide-DNA hybrids. For example, halo tags-DNA hybrid could be constructed as a handle 
and be linked covalently to halogenasecoated beads. Similarly, a peptide substrate to ubiquitin ligase could be used to generate peptide-DNA hybrid and then be linked to the protein ligase-coated bead. The reversibility of the ST-STN reaction, using Desthiobiotin [24], will make the ST-STN linkage also highly suitable for biologically inspired soft 12926553 matter systems, where reversibility could open up new possibilities.bind to MBP in the absence of ST (Experiment A) and cannot be eluted from amylose resin by maltose (Experiment B). Unlabeled MBP (0.15 mgr) was added to the STN (0.25 mgr) and the mixture was incubated for 1 hour in 4uC (Experiment A). The complex was then combined with amylose resin (for 2 hour in 4uC) and the resin subsequently was washed with maltose. SDS-PAGE showed STN band in master mixture (MBP+STN) (1) and supernatant sample (2), but no band was detected for eluted sample at the same location (3). This confirms that MBP-STN complex does not form specifically, in the absence of ST linkage. This process was repeated with the pure STN solution (Experiment B). The result shows that STN molecules which bind the column nonspecifically cannot be eluted by maltose. Overall, these control experiments indicate that the eluted STN molecules in Figure 1d, were linked via tST to MBP and confirm the chemical structure of the synthesized MBP-tST-STN complex. (TIF)Figure S2 Fraction of (NTV)biotin-DNA-Dig(AntiDig) tethers that resisted 60 pN in first and second pull, compared between different methods of Dig-AntiDig establishment. Connections can either form by incubation in bulk or in-situ within the tweezers apparatus by bringing the beads together. In blue bars, Dig-DNA-biotin molecules were incubated with NTV-coated beads, and the Dig-AntiDig connection was formed in-situ. In purple bars, Dig-DNA-biotin molecules were incubated with AntiDig-coated beads, and the biotin-NTV connection was formed in-situ. The statistics show a reduction in the fraction of survived tethers (both in the first and second pull) when Dig-AntiDig linkage formed in-situ. (TIF) Figure S3 Histogram of unbinding time of a tethered (NTV)biotin-DNA-Dig(AntiDig) held at overstretching, compared between different methods of Dig-AntiDig establishment. Peptide M custom synthesis linkages can either form by incubation in bulk or in-situ within the tweezers. In blue bars, Dig-DNA-biotin molecules were incubated with NTV-coated beads, and the 58-49-1 biological activity DigAntiDig connection was 15755315 formed in-situ within the tweezers. In purple bars, Dig-DNA-biotin molecules were incubated with AntiDig-coated beads, and the biotin-NTV connection was formed in-situ. The statistics show most of the in-situ formed DigAntiDig connections broke immediately (blue bars), while a few number of Dig-AntiDig linkages which formed by incubation (purple bars), broke within that time. (TIF)Supporting InformationFigure S1 The specificity of tST-STN interactions. (a) 1 Agarose gel showing protein-DNA hybrid (shown in Figure 1e) does not form in the absence of ST. Unlabeled DNA (25 ng) was mixed with a large excess of unlabeled MBP (3 mg) and STN (1 mg). The mixtures were incubated for 1 hour in 4uC and then loaded in to the 1.Shown that constructing tST-DNA hybrids is straightforward using PCR amplification, making our method suitable for broad applications. For single molecule studies, the presented approach could be applied in combination with other peptide-DNA hybrids. For example, halo tags-DNA hybrid could be constructed as a handle and be linked covalently to halogenasecoated beads. Similarly, a peptide substrate to ubiquitin ligase could be used to generate peptide-DNA hybrid and then be linked to the protein ligase-coated bead. The reversibility of the ST-STN reaction, using Desthiobiotin [24], will make the ST-STN linkage also highly suitable for biologically inspired soft 12926553 matter systems, where reversibility could open up new possibilities.bind to MBP in the absence of ST (Experiment A) and cannot be eluted from amylose resin by maltose (Experiment B). Unlabeled MBP (0.15 mgr) was added to the STN (0.25 mgr) and the mixture was incubated for 1 hour in 4uC (Experiment A). The complex was then combined with amylose resin (for 2 hour in 4uC) and the resin subsequently was washed with maltose. SDS-PAGE showed STN band in master mixture (MBP+STN) (1) and supernatant sample (2), but no band was detected for eluted sample at the same location (3). This confirms that MBP-STN complex does not form specifically, in the absence of ST linkage. This process was repeated with the pure STN solution (Experiment B). The result shows that STN molecules which bind the column nonspecifically cannot be eluted by maltose. Overall, these control experiments indicate that the eluted STN molecules in Figure 1d, were linked via tST to MBP and confirm the chemical structure of the synthesized MBP-tST-STN complex. (TIF)Figure S2 Fraction of (NTV)biotin-DNA-Dig(AntiDig) tethers that resisted 60 pN in first and second pull, compared between different methods of Dig-AntiDig establishment. Connections can either form by incubation in bulk or in-situ within the tweezers apparatus by bringing the beads together. In blue bars, Dig-DNA-biotin molecules were incubated with NTV-coated beads, and the Dig-AntiDig connection was formed in-situ. In purple bars, Dig-DNA-biotin molecules were incubated with AntiDig-coated beads, and the biotin-NTV connection was formed in-situ. The statistics show a reduction in the fraction of survived tethers (both in the first and second pull) when Dig-AntiDig linkage formed in-situ. (TIF) Figure S3 Histogram of unbinding time of 
a tethered (NTV)biotin-DNA-Dig(AntiDig) held at overstretching, compared between different methods of Dig-AntiDig establishment. Linkages can either form by incubation in bulk or in-situ within the tweezers. In blue bars, Dig-DNA-biotin molecules were incubated with NTV-coated beads, and the DigAntiDig connection was 15755315 formed in-situ within the tweezers. In purple bars, Dig-DNA-biotin molecules were incubated with AntiDig-coated beads, and the biotin-NTV connection was formed in-situ. The statistics show most of the in-situ formed DigAntiDig connections broke immediately (blue bars), while a few number of Dig-AntiDig linkages which formed by incubation (purple bars), broke within that time. (TIF)Supporting InformationFigure S1 The specificity of tST-STN interactions. (a) 1 Agarose gel showing protein-DNA hybrid (shown in Figure 1e) does not form in the absence of ST. Unlabeled DNA (25 ng) was mixed with a large excess of unlabeled MBP (3 mg) and STN (1 mg). The mixtures were incubated for 1 hour in 4uC and then loaded in to the 1.
