Journal of Molecular Evolution

, Volume 48, Issue 5, pp 528–541

RNA Polymerase of Aquifex pyrophilus: Implications for the Evolution of the Bacterial rpoBC Operon and Extremely Thermophilic Bacteria

  • Hans-Peter  Klenk
  • Thomas-Dirk  Meier
  • Peter  Durovic
  • Volker  Schwass
  • Friedrich  Lottspeich
  • Patrick P.  Dennis
  • Wolfram  Zillig

DOI: 10.1007/PL00006496

Cite this article as:
Klenk, HP., Meier, TD., Durovic, P. et al. J Mol Evol (1999) 48: 528. doi:10.1007/PL00006496

Abstract.

A 16,226-bp fragment from the genome of Aquifex pyrophilus was sequenced, containing the genes for ribosomal proteins L1, L10, and L7/12 (rplAJL), DNA-directed RNA polymerase subunits β and β′(rpoBC), alanyl-tRNA synthetase (alaS), and subunit A of proteinase Clp (clpA). Enzymatic activity and extreme thermostability of purified A. pyrophilus RNA polymerase were verified. Transcription initiation on a DNA construct harboring the T7 A1 promoter was demonstrated by elongation of a 32P-labeled trinucleotide. Phylogenetic analyses of the two largest subunits of bacterial RNA polymerases (β and β′) showed overall consistency with the 16S rRNA-based phylogeny, except for the positions of the hyperthermophiles A. pyrophilus and Thermotoga maritima and for the location of the root of the domain Bacteria. In the phylogenies for both RNA polymerase subunits β and β′, A. pyrophilus was placed within the Gram-negative bacteria below the ε subdivision of the Proteobacteria. No support was found for the 16S rRNA-based hypothesis that A. pyrophilus might be the deepest branch of the Bacteria, but the cell wall–less mycoplasmas were found with a high confidence at the root of the Bacteria phylogenies. This raised doubts not only about whether the original Bacteria were indeed like the hyperthermophiles, but also concerning the value of single-gene phylogenies for hypotheses about the evolution of organisms.

Key words: DNA-directed RNA polymerase —rpoBC operon — Extreme thermophiles —Aquifex pyrophilus—Thermotoga maritima—Mycoplasmatales— Molecular evolution 

Copyright information

© Springer-Verlag New York Inc. 1999

Authors and Affiliations

  • Hans-Peter  Klenk
    • 1
  • Thomas-Dirk  Meier
    • 2
  • Peter  Durovic
    • 3
  • Volker  Schwass
    • 2
  • Friedrich  Lottspeich
    • 2
  • Patrick P.  Dennis
    • 3
  • Wolfram  Zillig
    • 2
  1. 1.Georg-August-Universität Göttingen, Institut für Mikrobiologie und Genetik, Grisebachstraβe 8, 37077 Göttingen, GermanyDE
  2. 2.Max-Planck-Institut für Biochemie, 82152 Martinsried, GermanyDE
  3. 3.Department of Biochemistry and Molecular Biology, University of British Columbia, 2146 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3CA

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