In Vitro Synthesis and Properties of a φX DNA-RNA Hybrid
When the single-stranded DNA of bacteriophage φX174 is the primer for E. coli RNA polymerase, a DNA-RNA hybrid is formed. This hybrid, which has been isolated from a CsCl density gradient, melts over a relatively narrow temperature range. The hybrid is infective to bacterial protoplasts and the u.v. sensitivity of this infectivity is distinct from that of the free DNA. If the hybrid is denatured with formamide, the RNA may be recovered as fragments with a broad range of sedimentation coefficient from 6 to 14 s.
© 1964 Elsevier Ltd. Received 10 October 1963. We are much indebted to Dr. T. August and Dr. M. Chamberlin for assistance in the development of procedures for isolation of the RNA polymerase. dAT was a generous gift from Dr. R. Baldwin. This research was supported in part by a grant no, RG6965 from the U.S. Public Health Service.