Figure 7.

Selecting for strand displacement in an RNA polymerase ribozyme. A pool of potential strand displacing RNA polymerase ribozymes is tethered by a long flexible linker to a RNA (red strand) that is partially complementary to the template strand (bottom black strand). The unhybridized nucleotides in the red strand are not able to hybridize to the template strand resulting in the formation of an elongation complex mimic. Transcription by the tethered polymerase that is able to displace the red strand results in the polymerase disassociating from the extending primer template duplex (black strands). Freed polymerases can then be differentially recovered and amplified.