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| Title | Helicase-mediated mechanism of SSU processome maturation and disassembly. |
|---|---|
| Journal, issue, pages | Nature, Vol. 648, Issue 8094, Page 746-754, Year 2025 |
| Publish date | Oct 29, 2025 |
 Authors | Olga Buzovetsky / Sebastian Klinge /  |
| PubMed Abstract | Eukaryotic ribosomal small subunit (SSU) assembly requires the SSU processome, a nucleolar precursor containing the RNA chaperone U3 small nucleolar RNA (snoRNA). The underlying molecular mechanisms ...Eukaryotic ribosomal small subunit (SSU) assembly requires the SSU processome, a nucleolar precursor containing the RNA chaperone U3 small nucleolar RNA (snoRNA). The underlying molecular mechanisms of SSU processome maturation, remodelling, disassembly and RNA quality control, and the transitions between states remain unknown owing to a paucity of intermediates. Here we report 16 native SSU processome structures alongside genetic data, revealing how two helicases, the Mtr4-exosome and Dhr1, are controlled for accurate and unidirectional ribosome biogenesis. Our data show how irreversible pre-ribosomal RNA degradation by the redundantly tethered RNA exosome couples the transformation of the SSU processome into a pre-40S particle, during which Utp14 can probe evolving surfaces, ultimately positioning and activating Dhr1 to unwind the U3 snoRNA and initiate nucleolar pre-40S release. This study highlights a paradigm for large dynamic RNA-protein complexes in which irreversible RNA degradation drives compositional changes and communicates these changes to govern enzyme activity while maintaining overall quality control. |
 External links | Nature / PubMed:41162712 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 2.54 - 6.34 Å |
| Structure data |  EMDB-48938: SSU processome maturation and disassembly, State A* - Overall map  EMDB-48939: SSU processome maturation and disassembly, State A* - Bfr2Kre33 focused map  EMDB-48940: SSU processome maturation and disassembly, State A* - Core focused map  EMDB-48942: SSU processome maturation and disassembly, State A* - Noc4Nop14 focused map  EMDB-48943: SSU processome maturation and disassembly, State A* - Utp10 focused map  EMDB-48944: SSU processome maturation and disassembly, State A* - Utp20 focused map  EMDB-48945: SSU processome maturation and disassembly, State A* - UtpA focused map  EMDB-48946: SSU processome maturation and disassembly, State A* - UtpC focused map  EMDB-48947: SSU processome maturation and disassembly, State B - Overall map  EMDB-48948: SSU processome maturation and disassembly, State B - Bfr2Kre33 focused map  EMDB-48949: SSU processome maturation and disassembly, State B - Core focused map  EMDB-48950: SSU processome maturation and disassembly, State B - Noc4Nop14 focused map  EMDB-48952: SSU processome maturation and disassembly, State B - Utp20 focused map  EMDB-48953: SSU processome maturation and disassembly, State B - UtpA focused map  EMDB-48954: SSU processome maturation and disassembly, State B - UtpC focused map  EMDB-48955: SSU processome maturation and disassembly, State C - Overall map  EMDB-48956: SSU processome maturation and disassembly, State C - Bfr2Kre33 focused map  EMDB-48957: SSU processome maturation and disassembly, State C - Core focused map  EMDB-48958: SSU processome maturation and disassembly, State C - Noc4Nop14 focused map  EMDB-48959: SSU processome maturation and disassembly, State C - Utp20 focused map  EMDB-48960: SSU processome maturation and disassembly, State C - UtpA focused map  EMDB-48961: SSU processome maturation and disassembly, State C - UtpC focused map  EMDB-48962: SSU processome maturation and disassembly, State D - Overall map  EMDB-48963: SSU processome maturation and disassembly, State D - Bfr2Kre33 focused map  EMDB-48964: SSU processome maturation and disassembly, State D - Core focused map  EMDB-48965: SSU processome maturation and disassembly, State D - Utp20 focused map  EMDB-48966: SSU processome maturation and disassembly, State D - UtpA focused map  EMDB-48967: SSU processome maturation and disassembly, State D - H44 focused map  EMDB-48968: SSU processome maturation and disassembly, State D - UtpC focused map  EMDB-48969: SSU processome maturation and disassembly, State E - Overall map  EMDB-48970: SSU processome maturation and disassembly, State E - Dhr1 focused map  EMDB-48971: SSU processome maturation and disassembly, State E - Core focused map  EMDB-48972: SSU processome maturation and disassembly, State E - Utp20 focused map  EMDB-48973: SSU processome maturation and disassembly, State E - UtpA focused map  EMDB-48974: SSU processome maturation and disassembly, State E - UtpC focused map  EMDB-48975: SSU processome maturation and disassembly, State E - Noc4Nop14 focused map  EMDB-48985: SSU processome maturation and disassembly, State G - Overall map  EMDB-48986: SSU processome maturation and disassembly, State G - Dhr1 focused map  EMDB-48987: SSU processome maturation and disassembly, State G - Core focused map  EMDB-48988: SSU processome maturation and disassembly, State G - Utp20 focused map  EMDB-48989: SSU processome maturation and disassembly, State G - UtpA focused map  EMDB-48990: SSU processome maturation and disassembly, State G - UtpC focused map  EMDB-48991: SSU processome maturation and disassembly, State G - H44 focused map  EMDB-48992: SSU processome maturation and disassembly, State G - Noc4Nop14 focused map  EMDB-48993: SSU processome maturation and disassembly, State H - Overall map  EMDB-48994: SSU processome maturation and disassembly, State H - Dhr1 focused map  EMDB-48995: SSU processome maturation and disassembly, State H - Core focused map  EMDB-48996: SSU processome maturation and disassembly, State H - Utp20 focused map  EMDB-48997: SSU processome maturation and disassembly, State H - UtpA focused map  EMDB-48998: SSU processome maturation and disassembly, State H - UtpC focused map  EMDB-48999: SSU processome maturation and disassembly, State H - H44 focused map  EMDB-49000: SSU processome maturation and disassembly, State H - Noc4Nop14 focused map  EMDB-49001: SSU processome maturation and disassembly, State H - Utp10 focused map  EMDB-49002: SSU processome maturation and disassembly, State I - Overall map  EMDB-49003: SSU processome maturation and disassembly, State I - Dhr1 focused map  EMDB-49004: SSU processome maturation and disassembly, State I - Core focused map  EMDB-49005: SSU processome maturation and disassembly, State I - Utp20 focused map  EMDB-49006: SSU processome maturation and disassembly, State I - UtpA focused map  EMDB-49007: SSU processome maturation and disassembly, State I - UtpC focused map  EMDB-49008: SSU processome maturation and disassembly, State I - H44 focused map  EMDB-49009: SSU processome maturation and disassembly, State I - Noc4Nop14 focused map  EMDB-49010: SSU processome maturation and disassembly, State I - Utp10 focused map  EMDB-49011: SSU processome maturation and disassembly, State J - Overall map  EMDB-49012: SSU processome maturation and disassembly, State J - Core focused map  EMDB-49013: SSU processome maturation and disassembly, State J - Utp20 focused map  EMDB-49014: SSU processome maturation and disassembly, State J - UtpA focused map  EMDB-49015: SSU processome maturation and disassembly, State K - Overall map  EMDB-49016: SSU processome maturation and disassembly, State K - Core focused map  EMDB-49017: SSU processome maturation and disassembly, State K - Utp20 focused map  EMDB-49018: SSU processome maturation and disassembly, State K - UtpA focused map EMDB-49075, PDB-9n6v: EMDB-49076, PDB-9n6w: EMDB-49077, PDB-9n6x: EMDB-49078, PDB-9n6y: EMDB-49079, PDB-9n6z: EMDB-49080, PDB-9n70: EMDB-49083, PDB-9n73: EMDB-49084, PDB-9n74: EMDB-49085, PDB-9n75: EMDB-49086, PDB-9n76: EMDB-49087, PDB-9n77: EMDB-49090, PDB-9n7a: EMDB-49091, PDB-9n7b: |
| Chemicals |  ChemComp-MG:  ChemComp-ATP:  ChemComp-ZN:  ChemComp-GTP:  ChemComp-ADP: |
| Source |
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 Keywords | RIBOSOME / SSU processome / ribosome assembly / RNA folding / RNA-protein interactions |
Saccharomyces cerevisiae BY4741 (yeast)