title: Life without RNase P.
abstract: The universality of ribonuclease P (RNase P), the ribonucleoprotein essential for transfer RNA (tRNA) 5' maturation, 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.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.
authors.forename: Lennart
authors.initials: L
authors.lastname: Randau
authors.forename: Imke
authors.initials: I
authors.lastname: Schröder
authors.forename: Dieter
authors.initials: D
authors.lastname: Söll
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D049148:Aminoacylation; D001483:Base Sequence; D019143:Evolution, Molecular; D017353:Gene Deletion; D019766:Genes, Archaeal / Q000235:genetics*; D008954:Models, Biological; D008969:Molecular Sequence Data; D046588:Nanoarchaeota / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D019642:RNA, Archaeal / Q000235:genetics* / Q000378:metabolism; D012343:RNA, Transfer / Q000235:genetics* / Q000378:metabolism; D043262:Ribonuclease P / Q000172:deficiency* / Q000378:metabolism; D013379:Substrate Specificity; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D019642:RNA, Archaeal; D012343:RNA, Transfer; D043262:Ribonuclease P; D000604:Amino Acyl-tRNA Synthetases