Assembly and early maturation of large subunit precursors

Abstract

The eukaryotic ribosome is assembled through a complex process involving more than 200 factors. As pre-ribosomal RNA is transcribed, assembly factors bind the nascent pre-rRNA and guide its correct folding, modification and cleavage. While these early events in the assembly of the small ribosomal subunit have been relatively well-characterized, assembly of the large subunit precursors, or pre-60S, is less well understood. Recent structures of nucleolar intermediates of large subunit assembly have shed light on the role of many early large subunit assembly factors but how these particles emerge is still unknown. Here, we use the overexpression and purification of truncated pre-rRNAs to examine the initial assembly of pre-60S particles. Using this approach, we can recapitulate the early recruitment of large subunit assembly factors mainly to the domains I, II and VI of the assembling 25S rRNA.

RSL24D1 sustains steady-state ribosome biogenesis and pluripotency translational programs in embryonic stem cells

“…Conversely, RPL24 is almost exclusively present in the cytoplasm as described in yeast (42). In yeast, Rlp24 is assembled at the initial steps of pre-60S maturation corresponding to the state B (60), together with Tif6, Nog1 and Mak11 (23, 61), and then allows the recruitment of the hexameric Drg1 AAA-ATPase (42, 62). As the particles exit the nucleus, Drg1 gets activated by nucleoporins and releases Rlp24 from the pre-60S by mechanical force (42, 62-64), therefore allowing its substitution by the canonical ribosomal protein Rpl24.…”

RSL24D1 sustains steady-state ribosome biogenesis and pluripotency translational programs in embryonic stem cells

“…Considering the strong conservation of RSL24D1 structure and localization relative to its yeast homolog Rlp24, it is therefore likely that RSL24D1 shuttles between the nucleus and the cytoplasm 32 . In yeast, Rlp24 is assembled at the initial steps of pre-60S maturation 47 , together with Tif6, Nog1, and Mak11 16,48 , and then allows the recruitment of the hexameric Drg1 AAA-ATPase 32,49 . As the pre-LSU particles exit the nucleus, Drg1 gets activated by nucleoporins and releases Rlp24 by mechanical force, therefore allowing its substitution by the canonical ribosomal protein RPL24 32,49,50 .…”

Coupling of 5S RNP rotation with maturation of functional centers during large ribosomal subunit assembly

“…Rpf2 and Rrs1 may assemble into the subunit before the 5S RNP or they may all associate at the same time 22 , 23 . All of them co-purify with early nucleolar assembly intermediates 20 , 24 , 25 . However, they cannot be visualized on particles by cryo-electron microscopy (cryo-EM) until the formation of Nog2 State 1/State F/Arx1 particles during late nucleolar stages (middle stages) of 60S subunit assembly (Supplementary Figs.…”