RNase P without RNA: identification and functional reconstitution of the human mitochondrial tRNA processing enzyme.
Article Details
- CitationCopy to clipboard
Holzmann J, Frank P, Loffler E, Bennett KL, Gerner C, Rossmanith W
RNase P without RNA: identification and functional reconstitution of the human mitochondrial tRNA processing enzyme.
Cell. 2008 Oct 31;135(3):462-74. doi: 10.1016/j.cell.2008.09.013.
- PubMed ID
- 18984158 [ View in PubMed]
- Abstract
tRNAs are synthesized as immature precursors, and on their way to functional maturity, extra nucleotides at their 5' ends are removed by an endonuclease called RNase P. All RNase P enzymes characterized so far are composed of an RNA plus one or more proteins, and tRNA 5' end maturation is considered a universal ribozyme-catalyzed process. Using a combinatorial purification/proteomics approach, we identified the components of human mitochondrial RNase P and reconstituted the enzymatic activity from three recombinant proteins. We thereby demonstrate that human mitochondrial RNase P is a protein enzyme that does not require a trans-acting RNA component for catalysis. Moreover, the mitochondrial enzyme turns out to be an unexpected type of patchwork enzyme, composed of a tRNA methyltransferase, a short-chain dehydrogenase/reductase-family member, and a protein of hitherto unknown functional and evolutionary origin, possibly representing the enzyme's metallonuclease moiety. Apparently, animal mitochondria lost the seemingly ubiquitous RNA world remnant after reinventing RNase P from preexisting components.