Modular assembly of the nucleolar pre-60S ribosomal subunit

Modular assembly of the nucleolar pre-60S ribosomal subunit Nature 556, 7699 (2018). doi:10.1038/nature26156 Authors: Zahra Assur Sanghai, Linamarie Miller, Kelly R. Molloy, Jonas Barandun, Mirjam Hunziker, Malik Chaker-Margot, Junjie Wang, Brian T. Chait & Sebastian Klinge Early co-transcriptional events during eukaryotic ribosome assembly result in the formation of precursors of the small (40S) and large (60S) ribosomal subunits. A multitude of transient assembly factors regulate and chaperone the systematic folding of pre-ribosomal RNA subdomains. However, owing to a lack of structural information, the role of these factors during early nucleolar 60S assembly is not fully understood. Here we report cryo-electron microscopy (cryo-EM) reconstructions of the nucleolar pre-60S ribosomal subunit in different conformational states at resolutions of up to 3.4 Å. These reconstructions reveal how steric hindrance and molecular mimicry are used to prevent both premature folding states and binding of later factors. This is accomplished by the concerted activity of 21 ribosome assembly factors that stabilize and remodel pre-ribosomal RNA and ribosomal proteins. Among these factors, three Brix-domain proteins and their binding partners form a ring-like structure at ribosomal RNA (rRNA) domain boundaries to support the architecture of the maturing particle. The existence of mutually exclusive conformations of these pre-60S particles suggests that the fo...
Source: Nature - Category: Research Authors: Tags: Letter Source Type: research
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