RNA helicase Drs1 gates 25S rRNA domain III incorporation during early nucleolar pre-60S maturation

Authors

Thoms, M., Ayaz-Kök, S., Abe, K., Hamze, H., Thielen, A. S., Denk, T., Albert, B., Mikulic Vernik, N., Chitoiu, L., Laurent, E., Hurt, E., Henras, A. K., Beckmann, R., Mitterer, V.

Abstract

Assembly of eukaryotic large ribosomal subunits (LSU) requires coordinated structural and compositional transitions within pre-60S particles, yet the underlying mechanisms remain poorly understood. Here, we show that the DEAD-box helicase Drs1 promotes early maturation across distinct regions of the pre-60S particle. Loss of Drs1 function causes accumulation of co-transcriptional intermediates retaining SSU processome components, indicating that Drs1 promotes timely separation of nascent LSU precursors from the small-subunit assembly pathway. Cryo-EM analyses reveal both a redistribution toward early nucleolar maturation states upon loss of Drs1, including Nsa1-deficient intermediates, and a confinement of Drs1-associated particles to states preceding stable incorporation of 25S rRNA domain III. Drs1 directly engages Erb1 through its unstructured N-terminal extension, promoting stable assembly of the Nop7-Erb1-Ytm1 module associated with domain III maturation. CRAC analysis localizes Drs1 to spatially clustered sites spanning the 5.8S and 25S rRNAs, encompassing domains I-IV. Together, these findings support a model in which Drs1 couples stabilization of assembly-factors with pre-rRNA remodeling across the pre-60S particle, thereby driving ordered early LSU maturation and the timed integration of domain III.

Preprint server: bioRxiv
The authors list and abstract were imported from bioRxiv on 11 Sep 2026.

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