Fig. 2

cPPRs designed to bind to telomeric sequences. a Cartoon depicting the design and binding sites of cPPR-Telo1 and cPPR-Telo2. The amino acids at positions 5 and 35 of each repeat in the 10-repeat cPPRs are shown in red. The ssDNA probe is derived from the repeating telomeric DNA sequence and contains the binding sites for both cPPR-Telo1 and cPPR-Telo2. b ssDNA EMSA using Telo-ssDNA or poly(C) ssDNA (control). ssDNA–protein complexes are highlighted with red arrows. Protein concentrations used were, from left to right: 0, 0.15, 0.3, 0.5, 1, 2, 4, 6, 8 and 10 µM. c Inhibition of telomerase extension by telomere-targeting cPPRs in telomerase activity assays with immunopurified telomerase and a primer incorporating 18 nt of telomeric sequence. Increasing concentrations of cPPR-Telo1 and cPPR-Telo2 (50, 100, 200 and 300 nM) were added to the indicated reactions and cPPR-polyA and cPPR-polyC (300 nM, 1 µM and 3 µM) were used as control proteins. The red asterisk indicates a 30-mer 5′-³²P-labelled recovery/loading control. d Overall structure of cPPR-Telo1, shown in cartoon representation coloured in rainbow colours with blue at the N terminus and red at the C terminus. The surface charge distribution is coloured according to the local electrostatic potential (blue, +5 kT; red −5 kT). e Structure of cPPR-Telo1 in complex with DNA, which is shown as orange or yellow sticks