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Barandun J, Chaker-Margot M, Hunziker M, Molloy KR, Chait BT, Klinge S
Nat. Struct. Mol. Biol. 24 (11) 944-953 [2017-11-00; online 2017-09-25]
The small-subunit processome represents the earliest stable precursor of the eukaryotic small ribosomal subunit. Here we present the cryo-EM structure of the Saccharomyces cerevisiae small-subunit processome at an overall resolution of 3.8 Å, which provides an essentially complete near-atomic model of this assembly. In this nucleolar superstructure, 51 ribosome-assembly factors and two RNAs encapsulate the 18S rRNA precursor and 15 ribosomal proteins in a state that precedes pre-rRNA cleavage at site A1. Extended flexible proteins are employed to connect distant sites in this particle. Molecular mimicry and steric hindrance, as well as protein- and RNA-mediated RNA remodeling, are used in a concerted fashion to prevent the premature formation of the central pseudoknot and its surrounding elements within the small ribosomal subunit.
PubMed 28945246
DOI 10.1038/nsmb.3472
Crossref 10.1038/nsmb.3472
pii: nsmb.3472