Characterization of the DNA-melting function of the Rickettsia prowazekii RNA polymerase

Han Fei Ding, Herbert H. Winkler

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


In vitro specific transcription by the Rickettsia prowazekii RNA polymerase was investigated. The purified rickettsial RNA polymerase, in striking contrast to that of Escherichia coli, could specifically transcribe two R. prowazekii genes (ATP/ADP translocate and citrate synthase genes) and one E. coli gene (RNA-I) on negative supercoiled plasmids but not the same genes on linear plasmids. Following the specific binding of the rickettsial RNA polymerase to the translocase gene promoter on a linear plasmid, there was no detectable open complex formation. Both the E. coli and the R. prowazekii RNA polymerases worked well when poly(dA-dT)·poly(dA-dT) or poly(dI-dC)·poly-(dI-dC) was used as template for generalized transcription. However, the rickettsial RNA polymerase, in contrast to the E. coli enzyme, had little activity on poly(dG-dC)·poly(dG-dC), a template with a larger number of hydrogen bonds. These data indicate that the rickettsial RNA polymerase is weak, at least relative to E. coli, in the function required for the opening of DNA duplex. It appears that this operation in R. prowazekii is aided by the negative supercoiling and the high 72% AT composition of the rickettsial genome.

Original languageEnglish (US)
Pages (from-to)3897-3902
Number of pages6
JournalJournal of Biological Chemistry
Issue number6
StatePublished - Feb 25 1993
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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