Superfamily 1 Helicase Pif1 Can Push Replication Protein A Along Single Stranded Dna And Into Duplex Dna

Superfamily 1 helicase monomers are single stranded (ss) DNA translocases, but poor helicases. Replication protein A (RPA) is an ssDNA binding protein (SSB) that binds ssDNA with high affinity and can diffuse along ssDNA. On its own, RPA is capable of disrupting DNA secondary structure up to ∼7 base pairs (bp). We have previously shown using a novel single molecule total internal reflection fluorescence FRET assay that ssDNA translocases can push an E. coli SSB tetramer along ssDNA (Sokoloski et.al, PNAS.