期刊
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
卷 22, 期 11, 页码 -出版社
MDPI
DOI: 10.3390/ijms22116140
关键词
ribosome assembly; cryo-EM; 30S subunit maturation; RbfA; two-dimensional gel electrophoresis
资金
- Russian Science Foundation [RSF 19-74-20186]
- Russian Science Foundation [19-74-20186] Funding Source: Russian Science Foundation
Ribosome biogenesis is a complex and coordinated process, with cryo-electron microscopy revealing the role of the RbfA factor in the assembly of 30S ribosomal subunits, particularly in the formation of the central pseudoknot and positioning of helix 44.
Ribosome biogenesis is a highly coordinated and complex process that requires numerous assembly factors that ensure prompt and flawless maturation of ribosomal subunits. Despite the increasing amount of data collected, the exact role of most assembly factors and mechanistic details of their operation remain unclear, mainly due to the shortage of high-resolution structural information. Here, using cryo-electron microscopy, we characterized 30S ribosomal particles isolated from an Escherichia coli strain with a deleted gene for the RbfA factor. The cryo-EM maps for pre-30S subunits were divided into six classes corresponding to consecutive assembly intermediates: from the particles with a completely unresolved head domain and unfolded central pseudoknot to almost mature 30S subunits with well-resolved body, platform, and head domains and partially distorted helix 44. The structures of two predominant 30S intermediates belonging to most populated classes obtained at 2.7 angstrom resolutions indicate that RbfA acts at two distinctive 30S assembly stages: early formation of the central pseudoknot including folding of the head, and positioning of helix 44 in the decoding center at a later stage. Additionally, it was shown that the formation of the central pseudoknot may promote stabilization of the head domain, likely through the RbfA-dependent maturation of the neck helix 28. An update to the model of factor-dependent 30S maturation is proposed, suggesting that RfbA is involved in most of the subunit assembly process.
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