Minor changes largely restore catalytic activity of archaeal RNase P RNA from Methanothermobacter thermoautotrophicus.
The increased protein proportion of archaeal and eukaryal ribonuclease (RNase) P holoenzymes parallels a vast decrease in the catalytic activity of their RNA subunits (P RNAs) alone. We show that a few mutations toward the bacterial P RNA consensus substantially activate the catalytic (C-) domain of archaeal P RNA from Methanothermobacter, in the absence and presence of the bacterial RNase P protein. Large increases in ribozyme activity required the cooperative effect of at least two structural alterations. The P1 helix of P RNA from Methanothermobacter was found to be extended, which increases ribozyme activity (ca 200-fold) and stabilizes the tertiary structure. Activity increases of mutated archaeal C-domain variants were more pronounced in the context of chimeric P RNAs carrying the bacterial specificity (S-) domain of Escherichia coli instead of the archaeal S-domain. This could be explained by the loss of the archaeal S-domain's capacity to support tight and productive substrate binding in the absence of protein cofactors. Our results demonstrate that the catalytic capacity of archaeal P RNAs is close to that of their bacterial counterparts, but is masked by minor changes in the C-domain and, particularly, by poor function of the archaeal S-domain in the absence of archaeal protein cofactors.
Li
Dan
D
Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, D-35037 Marburg, Germany.
Willkomm
Dagmar K
DK
Hartmann
Roland K
RK
D001483:Base Sequence; D002384:Catalysis; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D020035:Holoenzymes / Q000378:metabolism; D007700:Kinetics; D017013:Methanobacteriaceae / Q000201:enzymology*; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D019642:RNA, Archaeal / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D043262:Ribonuclease P / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D029968:Escherichia coli Proteins; D020035:Holoenzymes; D019642:RNA, Archaeal; D043262:Ribonuclease P; C470865:ribonuclease P, E coli