title: Modular architecture of eukaryotic RNase P and RNase MRP revealed by electron microscopy.
abstract: Ribonuclease P (RNase P) and RNase MRP are closely related ribonucleoprotein enzymes, which process RNA substrates including tRNA precursors for RNase P and 5.8 S rRNA precursors, as well as some mRNAs, for RNase MRP. The structures of RNase P and RNase MRP have not yet been solved, so it is unclear how the proteins contribute to the structure of the complexes and how substrate specificity is determined. Using electron microscopy and image processing we show that eukaryotic RNase P and RNase MRP have a modular architecture, where proteins stabilize the RNA fold and contribute to cavities, channels and chambers between the modules. Such features are located at strategic positions for substrate recognition by shape and coordination of the cleaved-off sequence. These are also the sites of greatest difference between RNase P and RNase MRP, highlighting the importance of the adaptation of this region to the different substrates.
authors.affiliation: School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK.
authors.forename: Katharina
authors.initials: K
authors.lastname: Hipp
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Galani
authors.forename: Claire
authors.initials: C
authors.lastname: Batisse
authors.forename: Simone
authors.initials: S
authors.lastname: Prinz
authors.forename: Bettina
authors.initials: B
authors.lastname: Böttcher
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry; D004706:Endodeoxyribonucleases / Q000737:chemistry; D004722:Endoribonucleases / Q000737:chemistry* / Q000648:ultrastructure*; D008958:Models, Molecular; D021122:Protein Subunits / Q000737:chemistry; D012313:RNA / Q000737:chemistry; D043262:Ribonuclease P / Q000737:chemistry* / Q000648:ultrastructure*; D012260:Ribonucleases / Q000737:chemistry; D012261:Ribonucleoproteins / Q000737:chemistry; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry
chemical_list: D002352:Carrier Proteins; C484542:POP4 protein, S cerevisiae; C562233:Pop5 protein, S cerevisiae; D021122:Protein Subunits; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; D004706:Endodeoxyribonucleases; D004722:Endoribonucleases; C090162:PSO2 protein, S cerevisiae; D012260:Ribonucleases; C058330:mitochondrial RNA-processing endoribonuclease; C108353:RPP1 protein, S cerevisiae; D043262:Ribonuclease P