Figure 3.

Insertion of flexible polypeptide linkers does not disrupt nucleosome remodelling. (A) Remodelling activity was probed by following the accessibility of a unique, central KpnI restriction site in a 13-mer nucleosomal array (see schematic). Exemplary time courses for remodelling by ISWI_Wt and ISWI_{658:10 aa} (both 3 μM). In mock-treated samples (−ISWI), the KpnI site was not accessible. The original unspliced gel picture containing the mock-treated sample and the ISWI_Wt time-course is provided as supplementary Fig S2 online. (B,C) The observed rate constants for remodelling, k_obs, were determined for ISWI derivatives at the indicated concentrations by fitting time courses as in A to single exponential functions. Errors are s.d. for ISWI_{589:10 aa} and ISWI_{658:10 aa} (n=4 for 0.1 μM and 1 μM; n=3 for 3 μM) and 1 μM ISWI_Wt (n=3). In all other instances, minimal and maximal values of two independent measurements are shown. aa, amino acid; ISWI_Wt, wild-type ISWI; kb, kilobases.