Coordinated nuclear import of RNA polymerase III subunits.
Eukaryotic RNA polymerases are multisubunit assemblies, whose enzymatic function in the nucleus is intensively studied. However, little is known about the biogenesis of the three RNA polymerases and coupling to nucleo-cytoplasmic transport. Here, we show that Rpc128, the second largest subunit of RNA polymerase III, was mislocalized to the cytoplasm, when a short sequence in the N-terminal domain was deleted. Importantly, nuclear import of other, but not all, RNA polymerase III subunits was impaired in this RPC128DeltaN mutant. These data suggest that RNA polymerase III subunits are not imported independently into the nucleus but may require preassembly into cytoplasmic subcomplexes for coordinated nuclear uptake. We expect these studies to be a starting point to dissect the complex biogenesis pathway of eukaryotic RNA polymerases.
Biochemie-Zentrum der Universitat Heidelberg, INF328, D-69120 Heidelberg, Germany.
Ulrike
U
Hardeland
Ed
E
Hurt
D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000595:Amino Acid Sequence; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D021382:Protein Sorting Signals; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D012320:RNA Polymerase III / Q000235:genetics / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
D005656:Fungal Proteins; D046912:Multiprotein Complexes; D021382:Protein Sorting Signals; D021122:Protein Subunits; D012335:RNA, Ribosomal; D011993:Recombinant Fusion Proteins; D012343:RNA, Transfer; D012320:RNA Polymerase III