Translation initiation factor eIF3b contains a nine-bladed β-propeller and interacts with the 40S ribosomal subunit.
The multisubunit eukaryotic translation initiation factor 3, among which the subunit b (eIF3b) is a major scaffold protein, plays essential roles in protein synthesis. Here, we report the crystal structure of the WD40 domain of Chaetomium thermophilum eIF3b, revealing a nine-bladed β-propeller fold. Sequence analysis indicates that this propeller architecture is common to all eIF3b orthologs. Revisiting the cryoelectron microscopy (cryo-EM) map of the 43S preinitiation complex suggests an interaction of the eIF3b with the 40S ribosomal subunit involving the ribosomal protein S9e and the 18S rRNA. This model is strongly supported by the direct binding of eIF3b to 40S ribosomes and to the isolated ribosomal protein rpS9e in vitro.
Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany.
Yi
Y
Liu
Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany.
Piotr
P
Neumann
Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany.
Bernhard
B
Kuhle
Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany.
Thomas
T
Monecke
Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
Stephanie
S
Schell
Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
Ashwin
A
Chari
Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany. Electronic address: rficner@uni-goettingen.de.
Ralf
R
Ficner
D000595:Amino Acid Sequence; D001665:Binding Sites; D002597:Chaetomium / Q000737:chemistry / Q000235:genetics; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D039621:Eukaryotic Initiation Factor-3 / Q000737:chemistry* / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D021122:Protein Subunits; D054682:Ribosome Subunits, Small, Eukaryotic / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
D039621:Eukaryotic Initiation Factor-3; D005656:Fungal Proteins; D021122:Protein Subunits