파아지 T7전사종결제에 의한 파아지 SP6 와 T7 RNA 중합효소의전사종결반응

Abstract

Transcription termination efficiencies of a phage T7 terminator Tø for the T7 and SP6 RNA polymerases were studied. The terminator Tø cloned in the plasmid pET-3 was subcloned into the plasmid pGEM3Z which contains both SP6 and T7 RNA polymerase promoters facing each other. Amounts of transcripts terminated at Tø were compared with amounts of read-through transcripts run off at a restriction site. For quantitative analysis the transcripts were labeled with [α-^(32)P]rNTP in in vitro transcription reaction. Transcription of T7 RNA polymerase terminates with efficiency of 78% by the Tø in the pET-3, but terminates with efficiency of 38% by the Tø in the pGEM3Z. It suggests that DNA sequences other than the terminator sequence affect the termination efficiency. Interestingly, the Tø shows 81% termination efficiency for the SP6 RNA polymerase. Now this becomes the first strong terminator discovered for the SP6 RNA polymerase. This also suggests that both phage RNA polymerases might share similar mechanism of transcription termination.