Archives of Microbiology

, Volume 135, Issue 2, pp 103–109

RNA polymerase from Rhizobium japonicum

Authors

  • Brigitte Regensburger
    • Lehrstuhl für Mikrobiologie der Universität München
  • Hauke Hennecke
    • Lehrstuhl für Mikrobiologie der Universität München
Original Papers

DOI: 10.1007/BF00408017

Cite this article as:
Regensburger, B. & Hennecke, H. Arch. Microbiol. (1983) 135: 103. doi:10.1007/BF00408017

Abstract

DNA-dependend RNA polymerase (EC 2.7.7.6) from Rhizobium japonicum was purified. The subunit structure was found to be ββα2σ, with the following apparent molecular weights determined by electrophoresis: Mr (β and β') 150,000 each, Mr (σ) 96,000, Mr (α) 40,000, Mr (holoenzyme) 490,000, Mr (core enzyme) 380,000. The recovery of σ was 28%. RNA polymerase from aerobically grown R. japonicum cells and from nitrogen-fixing cells have the same electrophoretic properties suggesting that no chemical modification of the enzyme occurs when cells undergo this metabolic differentiation.

The enzyme is Mg2+-dependent, rifampicin-sensitive, and has optimal activity at alkaline pH (8–10) and at 35–40° C. It binds strongly to bacteriophage T7 promoters, weakly to antibiotic resistance genes, and not at all to cloned R. japonicum nif DNA. Preliminary in vitro transcription experiments, including nif DNA as template, revealed that additional factors may be required for selective transcription from promoters.

Key words

RNA polymeraseTranscriptionNitrogen fixationSymbiosisRhizobium

Copyright information

© Springer-Verlag 1983