The Pyrococcus exosome complex: structural and functional characterization.
The exosome is a conserved eukaryotic enzymatic complex that plays an essential role in many pathways of RNA processing and degradation. Here, we describe the structural characterization of the predicted archaeal exosome in solution using small angle x-ray scattering. The structure model calculated from the small angle x-ray scattering pattern provides an indication of the existence of a disk-shaped structure, corresponding to the "RNases PH ring" complex formed by the proteins aRrp41 and aRrp42. The RNases PH ring complex corresponds to the core of the exosome, binds RNA, and has phosphorolytic and polymerization activities. Three additional molecules of the RNA-binding protein aRrp4 are attached to the core as extended and flexible arms that may direct the substrates to the active sites of the exosome. In the presence of aRrp4, the activity of the core complex is enhanced, suggesting a regulatory role for this protein. The results shown here also indicate the participation of the exosome in RNA metabolism in Archaea, as was established in Eukarya.
Ramos
Celso Raul Romero
CR
Department of Biochemistry, Chemistry Institute, University of São Paulo, 05508-900 São Paulo, SP, Brazil.
Oliveira
Cristiano L P
CL
Torriani
Iris L
IL
Oliveira
Carla Columbano
CC
D019843:Archaeal Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D002850:Chromatography, Gel; D024202:Electrophoretic Mobility Shift Assay; D005095:Exoribonucleases / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D019711:Pyrococcus / Q000737:chemistry / Q000201:enzymology / Q000502:physiology*; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology*; D019642:RNA, Archaeal / Q000737:chemistry* / Q000502:physiology*; D012542:Scattering, Radiation; D012996:Solutions; D014961:X-Ray Diffraction; D014965:X-Rays
D019843:Archaeal Proteins; D019642:RNA, Archaeal; D012996:Solutions; D005095:Exoribonucleases