Comparison of fungal 80 S ribosomes by cryo-EM reveals diversity in structure and conformation of rRNA expansion segments.
Compared to the prokaryotic 70 S ribosome, the eukaryotic 80 S ribosome contains additional ribosomal proteins and extra segments of rRNA, referred to as rRNA expansion segments (ES). These eukaryotic-specific rRNA ES are mainly on the periphery of the 80 S ribosome, as revealed by cryo-electron microscopy (cryo-EM) studies, but their precise function is not known. To address the question of whether the rRNA ES are structurally conserved among 80 S ribosomes of different fungi we performed cryo-electron microscopy on 80 S ribosomes from the thermophilic fungus Thermomyces lanuginosus and compared it to the Saccharomyces cerevisiae 80 S ribosome. Our analysis reveals general structural conservation of the rRNA expansion segments but also changes in ES27 and ES7/39, as well as the absence of a tertiary interaction between ES3 and ES6 in T. lanuginosus. The differences provide a hint on the role of rRNA ES in regulating translation. Furthermore, we show that the stalk region and interactions with elongation factor 2 (eEF2) are different in T. lanuginosus, exhibiting a more extensive contact with domain I of eEF2.
Nilsson
Jakob
J
Department of Molecular Biology, University of Aarhus, Gustav Wieds vej 10C, DK-8000 Aarhus C, Denmark.
Sengupta
Jayati
J
Gursky
Richard
R
Nissen
Poul
P
Frank
Joachim
J
D020285:Cryoelectron Microscopy; D005656:Fungal Proteins / Q000648:ultrastructure; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D020652:Peptide Elongation Factor 2 / Q000378:metabolism; D011487:Protein Conformation; D012331:RNA, Fungal / Q000648:ultrastructure; D012335:RNA, Ribosomal / Q000648:ultrastructure; D012270:Ribosomes / Q000737:chemistry / Q000648:ultrastructure*; D012441:Saccharomyces cerevisiae / Q000235:genetics
D005656:Fungal Proteins; D020652:Peptide Elongation Factor 2; D012331:RNA, Fungal; D012335:RNA, Ribosomal