Fig. 2.

Pif1 enables fork progression through a dCas9 R-loop block on either the leading or lagging strand. (A) Illustration of the 3-kb forked DNA with either a leading or lagging strand dCas9 R-loop block. (B) Alkaline agarose gel of the results with or without dCas9 having a gRNA directed against the leading or lagging strand. Experiment staged as described in Methods, with the exception that 40 nM Pif1 was added for 5 min after the initial incubation with CMG, dCas9, and gRNA. Time courses include the first 5-min run-up to the block before the with or without Pif1 step.