5jpq

Publication Abstract from PubMed

The 90S pre-ribosome is an early biogenesis intermediate formed during co-transcriptional ribosome formation, composed of approximately 70 assembly factors and several small nucleolar RNAs (snoRNAs) that associate with nascent pre-rRNA. We report the cryo-EM structure of the Chaetomium thermophilum 90S pre-ribosome, revealing how a network of biogenesis factors including 19 beta-propellers and large alpha-solenoid proteins engulfs the pre-rRNA. Within the 90S pre-ribosome, we identify the UTP-A, UTP-B, Mpp10-Imp3-Imp4, Bms1-Rcl1, and U3 snoRNP modules, which are organized around 5'-ETS and partially folded 18S rRNA. The U3 snoRNP is strategically positioned at the center of the 90S particle to perform its multiple tasks during pre-rRNA folding and processing. The architecture of the elusive 90S pre-ribosome gives unprecedented structural insight into the early steps of pre-rRNA maturation. Nascent rRNA that is co-transcriptionally folded and given a particular shape by encapsulation within a dedicated mold-like structure is reminiscent of how polypeptides use chaperone chambers for their protein folding.

Architecture of the 90S Pre-ribosome: A Structural View on the Birth of the Eukaryotic Ribosome.,Kornprobst M, Turk M, Kellner N, Cheng J, Flemming D, Kos-Braun I, Kos M, Thoms M, Berninghausen O, Beckmann R, Hurt E Cell. 2016 Jul 14;166(2):380-93. doi: 10.1016/j.cell.2016.06.014. PMID:27419870^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.