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

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.

doi:10.64898/2026.09.05.749353

bioRxiv · 10.64898/2026.09.05.749353

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

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.

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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.

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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.. 2026-09-09. RNA helicase Drs1 gates 25S rRNA domain III incorporation during early nucleolar pre-60S maturation. https://doi.org/10.64898/2026.09.05.749353

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