Open AccessAssembly of the Trypanosoma brucei 60S Ribosomal Subunit Nuclear Export Complex Requires Trypanosome-Specific Proteins P34 and P37
Author(s) -
Kimberly M. Prohaska,
Noreen Williams
Publication year - 2009
Publication title -
eukaryotic cell
Language(s) - English
Resource type - Journals
eISSN - 1535-9778
pISSN - 1535-9786
DOI - 10.1128/ec.00234-08
Subject(s) - ribosomal protein , eukaryotic small ribosomal subunit , biology , trypanosoma brucei , eukaryotic large ribosomal subunit , ribosomal rna , 5s ribosomal rna , eukaryotic ribosome , ribosome biogenesis , ribosome , nuclear export signal , microbiology and biotechnology , protein subunit , rna , cell nucleus , biochemistry , 18s ribosomal rna , gene , nucleus
We previously identified twoTrypanosoma brucei RNA binding proteins, P34 and P37, and determined that they are essential for proper ribosomal assembly in this organism. Loss of these proteins via RNA interference is lethal and causes a decrease in both 5S rRNA levels and formation of 80S ribosomes, concomitant with a decrease in total cellular protein synthesis. These data suggest that these proteins are involved at some point in the ribosomal biogenesis pathway. In the current study, we have performed subcellular fractionation in conjunction with immune capture experiments specific for 60S ribosomal proteins and accessory factors in order to determine when and where P34 and P37 are involved in the ribosomal biogenesis pathway. These studies demonstrate that P34 and P37 associate with the 60S ribosomal subunit at the stage of the nucleolar 90S particle and remain associated subsequent to nuclear export. In addition, P34 and P37 associate with conserved 60S ribosomal subunit nuclear export factors exportin 1 and Nmd3, suggesting that they are components of the 60S ribosomal subunit nuclear export complex inT. brucei . Most significantly, the pre-60S complex does not associate with exportin 1 or Nmd3 in the absence of P34 and P37. These results demonstrate that, althoughT. brucei 60S ribosomal subunits utilize a nuclear export complex similar to that described for other organisms, trypanosome-specific factors are essential to the process.