Maturation of the 5S rRNA 5′ end is catalyzed in vitro by the endonuclease tRNase Z in the archaeon H. volcanii

Annette Holzle, Susan Fischer, Ruth Heyer, Stefanie Schütz, Martin Zacharias, Paul Walther, Thorsten Allers, Anita Marchfelder

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Ribosomal RNA molecules are synthesized as precursors that have to undergo several processing steps to generate the functional rRNA. The 5S rRNA in the archaeon Haloferax volcanii is transcribed as part of a multicistronic transcript containing both large rRNAs and one or two tRNAs. Release of the 5S rRNA from the precursor requires two endonucleolytic cleavages by enzymes as yet not identified. Here we report the first identification of an archaeal 5S rRNA processing endonuclease. The enzyme tRNase Z, which was initially identified as tRNA processing enzyme, generates not only tRNA 39 ends but also mature 5S rRNA 5′ ends in vitro. Interestingly, the sequence upstream of the 5S rRNA can be folded into a mini-tRNA, which might explain the processing of this RNA by tRNase Z. The endonuclease is active only at low salt concentrations in vitro, which is in contrast to the 2-4 M KCl concentration present inside the cell in vivo. Electron microscopy studies show that there are no compartments inside the Haloferax cell that could provide lower salt environments. Processing of the 5S rRNA 5′ end is not restricted to the haloarchaeal tRNase Z since tRNase Z enzymes from a thermophilic archaeon, a lower and a higher eukaryote, are as well able to cleave the tRNA-like structure 5′ of the 5S rRNA. Knock out of the tRNase Z gene in Haloferax volcanii is lethal, showing that the protein is essential for the cell. Published by Cold Spring Harbor Laboratory Press.

Original languageEnglish
Pages (from-to)928-937
Number of pages10
Issue number5
StatePublished - May 2008
Externally publishedYes


  • Archaea
  • Haloferax volcanii
  • RNase Z
  • rRNA processing
  • tRNA processing
  • tRNase Z


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