Protein components contribute to active site architecture for eukaryotic ribonuclease P.
In eukaryotes, ribonuclease P (RNase P) requires both RNA and protein components for catalytic activity. The eukaryotic RNase P RNA, unlike its bacterial counterparts, does not possess intrinsic catalytic activity in the absence of holoenzyme protein components. We have used a sensitive photoreactive cross-linking assay to explore the substrate-binding environment for different eukaryotic RNase P holoenzymes. Protein components from the Tetrahymena thermophila and human RNase P holoenzymes form specific products in photoreactions containing [4-thio]-uridine-labeled pre-tRNAGln. The HeLa RNase P RNA in neither the presence nor the absence of holoenzyme protein components formed cross-link products to the pre-tRNAGln probe. Parallel photo-cross-linking experiments with the Escherichia coli RNase P holoenzyme revealed that only the bacterial RNase P RNA forms specific substrate photoadducts. A protein-rich active site for the eukaryotic RNase P represents one unique feature that distinguishes holoenzyme organization between bacteria and eukaryotes.
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Department of Microbiology, University of Illinois at Urbana-Champaign, Chemical and Life Sciences Laboratory, Urbana, Illinois 61801, USA.
Celander
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D000818:Animals; D001665:Binding Sites; D004722:Endoribonucleases / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D011487:Protein Conformation; D012322:RNA Precursors / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry / Q000378:metabolism*; D043262:Ribonuclease P; D016808:Tetrahymena thermophila
D029968:Escherichia coli Proteins; D012322:RNA Precursors; D016337:RNA, Catalytic; D004722:Endoribonucleases; C468368:RPP14 protein, human; D043262:Ribonuclease P; C470865:ribonuclease P, E coli