Two archaeal tRNase Z enzymes: similar but different

• Published in: Archives of microbiology Vol. 190; no. 3; pp. 301 - 308
• Main Authors: Späth, Bettina, Schubert, Sylvia, Lieberoth, Annika, Settele, Florian, Schütz, Stefanie, Fischer, Susan, Marchfelder, Anita
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.09.2008; Springer-Verlag; Springer Nature B.V
• Subjects: Archaeal Proteins - metabolism; Biochemistry; Biomedical and Life Sciences; Biotechnology; Cell Biology; Cloning, Molecular; DNA, Archaeal - genetics; Ecology; Electrophoretic Mobility Shift Assay; Endoribonucleases - drug effects; Endoribonucleases - genetics; Endoribonucleases - metabolism; Escherichia coli - enzymology; Escherichia coli - genetics; Haloferax volcanii; Haloferax volcanii - enzymology; Haloferax volcanii - genetics; Ions; Life Sciences; Metallo-β-lactamase; Metals, Heavy - metabolism; Microbial Ecology; Microbiology; Original Paper; Potassium Chloride - pharmacology; Pyrococcus furiosus; Pyrococcus furiosus - enzymology; Pyrococcus furiosus - genetics; RNA Precursors - metabolism; RNA Processing, Post-Transcriptional; RNA, Archaeal - metabolism; RNA, Transfer - metabolism; Substrate Specificity; tRNA Processing; tRNase Z; tRNase Z; Metallo-β-lactamase; tRNA Processing
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s00203-008-0368-4

The endoribonuclease tRNase Z plays an essential role in tRNA metabolism by removal of the 3' trailer element of precursor RNAs. To investigate tRNA processing in archaea, we identified and expressed the tRNase Z from Haloferax volcanii, a halophilic archaeon. The recombinant enzyme is a homodimer and efficiently processes precursor tRNAs. Although the protein is active in vivo at 2-4 M KCl, it is inhibited by high KCl concentrations in vitro, whereas 2-3 M (NH₄)₂SO₄ do not inhibit tRNA processing. Analysis of the metal content of the metal depleted tRNase Z revealed that it still contains 0.4 Zn²⁺ ions per dimer. In addition tRNase Z requires Mn²⁺ ions for processing activity. We compared the halophilic tRNase Z to the homologous one from Pyrococcus furiosus, a thermophilic archaeon. Although both enzymes have 46% sequence similarity, they differ in their optimal reaction conditions. Both archaeal tRNase Z proteins process mitochondrial pre-tRNAs. Only the thermophilic tRNase Z shows in addition activity toward intron containing pre-tRNAs, 5' extended precursors, the phosphodiester bis(p-nitrophenyl)phosphate (bpNPP) and the glyoxalase II substrate S-d-lactoylglutathion (SLG).