The essential Drosophila ATP-binding cassette domain protein, pixie, binds the 40 S ribosome in an ATP-dependent manner and is required for translation initiation.
The Drosophila gene, pixie, is an essential gene required for normal growth and translation. Pixie is the fly ortholog of human RLI, which was first identified as an RNase L inhibitor, and yeast Rli1p, which has recently been shown to play a role in translation initiation and ribosome biogenesis. These proteins are all soluble ATP-binding cassette proteins with two N-terminal iron-sulfur clusters. Here we demonstrate that Pixie can be isolated from cells in complex with eukaryotic translation initiation factor 3 and ribosomal proteins of the small subunit. In addition, our analysis of polysome profiles reveals that double-stranded RNA interference-mediated depletion of Pixie results in an increase in empty 80 S ribosomes and a corresponding decrease in polysomes. Thus Pixie is required for normal levels of translation initiation. We also find that Pixie associates with the 40 S subunit on sucrose density gradients in an ATP-dependent manner. Our observations are consistent with Pixie playing a catalytic role in the assembly of complexes required for translation initiation. Thus, the function of this soluble ATP-binding cassette domain protein family in translation initiation has been conserved from yeast through to higher eukaryotes.
Andersen
Ditte S
DS
Growth Regulation Laboratory, Cancer Research UK London Research Institute, P O Box 123, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom.
Leevers
Sally J
SJ
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D039621:Eukaryotic Initiation Factor-3 / Q000378:metabolism*; D006801:Humans; D010442:Peptide Chain Initiation, Translational / Q000502:physiology*; D011132:Polyribosomes / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology
D018528:ATP-Binding Cassette Transporters; D029721:Drosophila Proteins; D039621:Eukaryotic Initiation Factor-3; C521107:pix protein, drosophila; D000255:Adenosine Triphosphate