Structural highlights
Function[MDN1_SCHPO] 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.[UniProtKB:Q12019] Publication Abstract from PubMedMdn1 is an essential AAA (ATPase associated with various activities) protein that removes assembly factors from distinct precursors of the ribosomal 60S subunit. However, Mdn1's large size ( approximately 5,000 amino acid [aa]) and its limited homology to other well-studied proteins have restricted our understanding of its remodeling function. Here, we present structures for S. pombe Mdn1 in the presence of AMPPNP at up to approximately 4 A or ATP plus Rbin-1, a chemical inhibitor, at approximately 8 A resolution. These data reveal that Mdn1's MIDAS domain is tethered to its ring-shaped AAA domain through an approximately 20 nm long structured linker and a flexible approximately 500 aa Asp/Glu-rich motif. We find that the MIDAS domain, which also binds other ribosome-assembly factors, docks onto the AAA ring in a nucleotide state-specific manner. Together, our findings reveal how conformational changes in the AAA ring can be directly transmitted to the MIDAS domain and thereby drive the targeted release of assembly factors from ribosomal 60S-subunit precursors. Structural Insights into Mdn1, an Essential AAA Protein Required for Ribosome Biogenesis.,Chen Z, Suzuki H, Kobayashi Y, Wang AC, DiMaio F, Kawashima SA, Walz T, Kapoor TM Cell. 2018 Oct 18;175(3):822-834.e18. doi: 10.1016/j.cell.2018.09.015. Epub 2018 , Oct 11. PMID:30318141[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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