6ylf
Rix1-Rea1 pre-60S particle - Rea1, body 3 (rigid body refinement, composite structure of Rea1 ring and tail)
Structural highlights
FunctionMDN1_YEAST Nuclear chaperone required for maturation and nuclear export of pre-60S ribosome subunits. Functions at successive maturation steps to remove ribosomal factors at critical transition points, first driving the exit of early pre-60S particles from the nucleolus and then driving late pre-60S particles from the nucleus. Mediates ATP-dependent remodeling of the pre-ribosome just prior to export to allow maturation of 60S subunits into export-competent particles. Removes the ribosome biogenesis factor RSA4 from pre-60S ribosomal subunits in the nucleoplasm to drive nuclear export of the subunit. Involved in 3' processing of the 5.8S rRNA.[1] [2] [3] [4] Publication Abstract from PubMedRibosome assembly is driven by numerous assembly factors, including the Rix1 complex and the AAA ATPase Rea1. These two assembly factors catalyze 60S maturation at two distinct states, triggering poorly understood large-scale structural transitions that we analyzed by cryo-electron microscopy. Two nuclear pre-60S intermediates were discovered that represent previously unknown states after Rea1-mediated removal of the Ytm1-Erb1 complex and reveal how the L1 stalk develops from a pre-mature nucleolar to a mature-like nucleoplasmic state. A later pre-60S intermediate shows how the central protuberance arises, assisted by the nearby Rix1-Rea1 machinery, which was solved in its pre-ribosomal context to molecular resolution. This revealed a Rix12-Ipi32 tetramer anchored to the pre-60S via Ipi1, strategically positioned to monitor this decisive remodeling. These results are consistent with a general underlying principle that temporarily stabilized immature RNA domains are successively remodeled by assembly factors, thereby ensuring failsafe assembly progression. Construction of the Central Protuberance and L1 Stalk during 60S Subunit Biogenesis.,Kater L, Mitterer V, Thoms M, Cheng J, Berninghausen O, Beckmann R, Hurt E Mol Cell. 2020 Aug 20;79(4):615-628.e5. doi: 10.1016/j.molcel.2020.06.032. Epub, 2020 Jul 14. PMID:32668200[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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