title: Mycoplasma fermentans simplifies our view of the catalytic core of ribonuclease P RNA.
abstract: The catalytic RNA moiety of (eu)bacterial RNase P is responsible for cleavage of the 5' leader sequence from precursor tRNAs. We report the sequence, the catalytic properties, and a phylogenetic-comparative structural analysis of the RNase P RNA from Mycoplasma fermentans, at 276 nt the smallest known RNase P RNA. This RNA is noteworthy in that it lacks a stem-loop structure (helix P12) that was thought previously to be universally present in bacterial RNase P RNAs. This finding suggests that helix P12 is not required for catalytic activity in vivo. In order to test this possibility in vitro, the kinetic properties of M. fermentans RNase P RNA and a mutant Escherichia coli RNase P RNA that was engineered to lack helix P12 were determined. These RNase P RNAs are catalytically active with efficiencies (Kcat/Km) comparable to that of native E. coli RNase P RNA. These results show that helix P12 is dispensable in vivo in some organisms, and therefore is unlikely to be essential for the mechanism of RNase P action. The notion that all phylogenetically volatile structures in RNase P RNA are dispensable for the catalytic mechanism was tested. A synthetic RNA representing the phylogenetic minimum RNase P RNA was constructed by deleting all evolutionarily variable structures from the M. fermentans RNA. This simplified RNA (Micro P RNA) was catalytically active in vitro with approximately 600-fold decrease in catalytic efficiency relative to the native RNA.
authors.affiliation: Department of Biology, Indiana University, Bloomington, 47405, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Siegel
authors.forename: A B
authors.initials: AB
authors.lastname: Banta
authors.forename: E S
authors.initials: ES
authors.lastname: Haas
authors.forename: J W
authors.initials: JW
authors.lastname: Brown
authors.forename: N R
authors.initials: NR
authors.lastname: Pace
mesh_terms: D001483:Base Sequence; D002384:Catalysis; D004722:Endoribonucleases / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D016858:Mycoplasma fermentans / Q000201:enzymology*; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D016337:RNA, Catalytic / Q000235:genetics* / Q000378:metabolism; D043262:Ribonuclease P; D013329:Structure-Activity Relationship
chemical_list: D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D016337:RNA, Catalytic; D004722:Endoribonucleases; D043262:Ribonuclease P; C470865:ribonuclease P, E coli