Figure 5. Cas4 family proteins are specific for single-stranded DNA and stalled by an internal extrahelical fluorescein.

The left side of the gel shows degradation of a 31nt oligonucleotide with an internal fluorescein-dT at position 20. The right hand side shows this oligonucleotide in a 31bp DNA duplex (both at 1 µM final concentration). The assay was carried out with 0.6 µM Sso0001 at 55°C for time points of 0, 1, 2, 3, 5, 10, 20, 30 and 40 min in 10 mM Mg²⁺. Control lanes (c) lacked added Sso0001 enzyme.