Life without RNase P


The universality of ribonuclease P (RNase P), the ribonucleoprotein essential for transfer RNA (tRNA) 5′ maturation1,2, is challenged in the archaeon Nanoarchaeum equitans. Neither extensive computational analysis of the genome nor biochemical tests in cell extracts revealed the existence of this enzyme. Here we show that the conserved placement of its tRNA gene promoters allows the synthesis of leaderless tRNAs, whose presence was verified by the observation of 5′ triphosphorylated mature tRNA species. Initiation of tRNA gene transcription requires a purine, which coincides with the finding that tRNAs with a cytosine in position 1 display unusually extended 5′ termini with an extra purine residue. These tRNAs were shown to be substrates for their cognate aminoacyl-tRNA synthetases. These findings demonstrate how nature can cope with the loss of the universal and supposedly ancient RNase P through genomic rearrangement at tRNA genes under the pressure of genome condensation.

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Figure 1: RNase P cleavage assay and tRNA genes in N. equitans.
Figure 2: Strict tRNA gene promoter placement in N. equitans.
Figure 3: Detection of triphosphorylated tRNA.
Figure 4: A scenario that allows the loss of RNase P.


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We thank P. O’Donoghue, J. Yuan and L. Sherrer for help and encouragement. This work was supported by grants from the National Institute of General Medical Sciences and the Department of Energy (D.S.) and the National Science Foundation (I.S.).

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Correspondence to Dieter Söll.

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Randau, L., Schröder, I. & Söll, D. Life without RNase P. Nature 453, 120–123 (2008) doi:10.1038/nature06833

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