Open AccessNovel template requirements of N4 virion RNA polymerase.
Author(s) -
S. Carl Falco,
Robert A. Zivin,
Lucia B. Rothman-Denes
Publication year - 1978
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.75.7.3220
Subject(s) - rna dependent rna polymerase , microbiology and biotechnology , polymerase , transcription (linguistics) , rna polymerase , biology , rna , dna , dna clamp , rna polymerase ii , dna gyrase , rna polymerase i , dna polymerase , biochemistry , escherichia coli , reverse transcriptase , gene expression , gene , promoter , linguistics , philosophy
A DNA-dependent RNA polymerase has been purified from disrupted virions of the Escherichia coli bacteriophage N4. The RNA polymerase is phage-coded and is required for class I N4 RNA synthesis, which is defined as RNA synthesized in vivo in the absence of post-infection protein synthesis. A polypeptide of molecular weight 350,000 is detected when the purified enzyme is analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. N4 RNA polymerase requires denatured DNA as a template in vitro and shows a strong preference for denatured N4 DNA. With this template, transcription is asymmetric. The RNA product is complementary to only the H strand of N4 DNA. Furthermore, only class I N4 RNA is synthesized. In vivo transcription by the N4 virion RNA polymerase is inhibited by coumermycin. This result suggests that the activity of E. coli DNA gyrase, an enzyme that introduces negative supertwists into DNA, is required for N4 transcription.