Two archaeal tRNase Z enzymes: similar but different.
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)(2)SO4 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).
Späth
Bettina
B
Valckenburg Schule, Valckenburgufer 21, 89073 Ulm, Germany.
Schubert
Sylvia
S
Lieberoth
Annika
A
Settele
Florian
F
Schütz
Stefanie
S
Fischer
Susan
S
Marchfelder
Anita
A
D019843:Archaeal Proteins / Q000378:metabolism; D003001:Cloning, Molecular; D019641:DNA, Archaeal / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D004722:Endoribonucleases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D019622:Haloferax volcanii / Q000201:enzymology* / Q000235:genetics; D019216:Metals, Heavy / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D020027:Pyrococcus furiosus / Q000201:enzymology / Q000235:genetics; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D019642:RNA, Archaeal / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism*; D013379:Substrate Specificity
D019843:Archaeal Proteins; D019641:DNA, Archaeal; D019216:Metals, Heavy; D012322:RNA Precursors; D019642:RNA, Archaeal; D011189:Potassium Chloride; D012343:RNA, Transfer; D004722:Endoribonucleases