(d) Hel308 DNA helicase DNA (pdb 2PR6; backbone in orange, bases in gray bonds) after aligning the RecA domains of Hel308 with those of FRH (cyan, RNA in yellow); see also Appendix Fig S4. The superposition indicates that the KOW module is positioned to interact with double stranded RNA that is being unwound by the RecA and DHSCT domains. 