RNA helicase Drs1 gates 25S rRNA domain III incorporation during early nucleolar pre-60S maturation
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…
A recent study has shed light on the crucial role played by RNA helicase Drs1 in the early maturation of eukaryotic large ribosomal subunits (LSU). The research reveals that Drs1 promotes timely separation of nascent LSU precursors from the small-subunit assembly pathway, ensuring a smooth progression towards stable incorporation of 25S rRNA domain III.
The study employed cryo-EM analyses to observe the structural changes that occur in Drs1-associated particles upon its loss. These changes include a redistribution towards early nucleolar maturation states and confinement to states preceding stable incorporation of 25S rRNA domain III. Furthermore, Drs1 directly engages Erb1 through its unstructured N-terminal extension, which facilitates the stable assembly of the Nop7-Erb1-Ytm1 module associated with domain III maturation.
The findings highlight the importance of Drs1 in coupling stabilization of assembly-factors with pre-rRNA remodeling across the pre-60S particle. By doing so, Drs1 drives ordered early LSU maturation and the timely integration of domain III, ultimately contributing to the overall formation of functional ribosomes.
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