TRANSCRIPTION OF RNA TEMPLATES BY T7 RNA-POLYMERASE

Although highly specialized, T7 RNA polymerase seems to possess a larg e range of DNA- and RNA-dependent properties. To study such flexibilit y, we determined the ability of T7 RNA polymerase to transcribe chimer ic DNA-RNA and RNA templates following initiation at a double stranded DNA promoter. We have found that T7 RNA polymerase is able to initiat e on RNA templates, was processive, and was able to use templates cont aining RNA-RNA duplexes under standard transcription conditions. Impli cations of remnants of such RNA-dependent activities for T7 DNA-depend ent polymerase are discussed.