Fig. 4. Curaxins and competitor nucleosomes synergistically inhibit FACT-dependent transcription in vitro.

(A) Experimental approach. The assembled Pol II EC-119 was ligated to the 603 DNA or nucleosome (43, 58). The RNA was pulse labeled in the presence of a subset of NTPs and [α-³²P]GTP, and Pol II was stalled at position −83 (43, 45, 58). Then, transcription was resumed by adding all unlabeled NTPs, FACT (to 0.2 μM), unlabeled competitor nucleosomes, and CBL0100 (B) or CBL0137 (C). Note that without competitor nucleosomes, curaxins moderately stimulate transcription through chromatin but do not inhibit FACT action. UTP, uridine 5′-triphosphate.