Assembly of Bacterial Ribosomes

Abstract

The assembly of ribosomes from a discrete set of components is a key aspect of the highly coordinated process of ribosome biogenesis. In this review, we present a brief history of the early work on ribosome assembly in Escherichia coli, including a description of in vivo and in vitro intermediates. The assembly process is believed to progress through an alternating series of RNA conformational changes and protein-binding events; we explore the effects of ribosomal proteins in driving these events. Ribosome assembly in vivo proceeds much faster than in vitro, and we outline the contributions of several of the assembly cofactors involved, including Era, RbfA, RimJ, RimM, RimP, and RsgA, which associate with the 30S subunit, and CsdA, DbpA, Der, and SrmB, which associate with the 50S subunit.

A hierarchical model for assembly of eukaryotic 60S ribosomal subunit domains

“…(The 59 end of 27SA 2 pre-rRNA is ;150 nucleotides [nt] upstream of what becomes the 59 end of mature 5.8S rRNA, while the 39 end of 27SA 2 pre-rRNA is identical to the 39 end of 25S rRNA.) These sequences might have to be juxtaposed during an early compaction event to commence 60S assembly, similar to bacterial large subunit assembly where sequences flanking 23S rRNA form a helix recognized by RNase III (Shajani et al 2011). The bacterial homolog of L3 occupies a similar position close to the ends of 23S rRNA and is required to initiate 50S assembly (Nowotny and Nierhaus 1982).…”

“…Folding of rRNAs creates binding sites for primary RPs. Their binding induces conformational changes in rRNA, which enables the subsequent assembly of secondary and tertiary binding RPs (Shajani et al 2011;Woodson 2011). More recent studies have shown that assembly in vitro can proceed via parallel pathways (Adilakshmi et al 2008;Mulder et al 2010) in which individual RPs contact different rRNA elements in multiple stages throughout assembly.…”

De novo design of an RNA tile that self-assembles into a homo-octameric nanoprism

“…Here we expand the design principle to achieve higher structural complexity along this direction. Besides addressing the fundamental challenge in programmed RNA self-assembly, we believe that such a study will increase our capability of rationally designing RNA nanostructures 33,34 to meet the needs of potential applications such as siRNA delivery 5,6 and construction of in vivo RNA machineries 4 . In addition, we have observed a surprising but interesting phenomenon.…”

“…S elf-assembled RNA nanostructures could potentially provide a platform to integrate a wide range of structural motifs and functionalities associated with RNA molecules, such as specific chemical binding 1 , catalysis capability 2 , gene regulation 3 and organizing proteins into large machineries 4 . They promise many technological applications, such as drug delivery 5,6 and arranging chemical reactions to produce useful chemicals 7 .…”

Single methylation of 23S rRNA triggers late steps of 50S ribosomal subunit assembly

“…Each subunit can be reconstituted in vitro from its individual component ribosomal RNAs and proteins (1)(2)(3)(4)(5), indicating that these components contain all of the information necessary to automatically assemble into functional subunits. Because the intermediate particles observed in an in vitro reconstitution of the subunits are similar to those observed in vivo, assembly maps that describe the order of ribosomal protein binding in vitro are useful tools for understanding ribosome biogenesis in the cell (6). However, assembly is slower in vitro than in vivo, and nonphysiological conditions, such as high-salt concentration and high temperature, are required for in vitro assembly.…”