bims-tricox 2025-05-25 papers

Mol Cell. 2025 May 15. pii: S1097-2765(25)00365-X. [Epub ahead of print]85(10): 1891-1893

Quality control of ribosome assembly: Kinetic discrimination at work.

Ribosome biogenesis is a complex and error-prone process, necessitating quality control mechanisms to degrade defective pre-ribosomal intermediates. In this issue of Molecular Cell, Akers et al.1 report the identification of a previously uncharacterized quality control pathway named ribosome assembly surveillance pathway (RASP), which functions to eliminate aberrant "dead-end" pre-60S assembly intermediates.

DOI: https://doi.org/10.1016/j.molcel.2025.04.023

Science. 2025 May 22. eadr3498

Silencing mitochondrial gene expression in living cells.

Mitochondria fulfill central functions in metabolism and energy supply. They express their own genome, which encodes key subunits of the oxidative phosphorylation system. However, central mechanisms underlying mitochondrial gene expression remain enigmatic. A lack of suitable technologies to target mitochondrial protein synthesis in cells has limited experimental access. Here, we silenced the translation of specific mitochondrial mRNAs in living human cells by delivering synthetic peptide-morpholino chimeras. This approach allowed us to perform a comprehensive temporal monitoring of cellular responses. Our study provides insights into mitochondrial translation, its integration into cellular physiology, and provides a strategy to address mitochondrial gene expression in living cells. The approach can potentially be used to analyze mechanisms and pathophysiology of mitochondrial gene expression in a range of cellular model systems.

DOI: https://doi.org/10.1126/science.adr3498

Nat Commun. 2025 May 21. 16(1): 4720

H/ACA snR30 snoRNP guides independent 18S rRNA subdomain formation.

Paulina Fischer, Matthias Thoms, Benjamin Lau, Timo Denk, Maria Kuvshinova, Otto Berninghausen, Dirk Flemming, Ed Hurt, Roland Beckmann.

Ribosome biogenesis follows a cascade of pre-rRNA folding and processing steps, coordinated with ribosomal protein incorporation. Nucleolar 90S pre-ribosomes are well-described stable intermediates, composed of pre-18S rRNA, ribosomal S-proteins, U3 snoRNA, and ~70 assembly factors. However, how numerous snoRNAs control pre-rRNA modification and folding during early maturation events remains unclear. We identify snR30 (human U17), the only essential H/ACA snoRNA in yeast, which binds with Cbf5-Gar1-Nop10-Nhp2 to a pre-18S rRNA subdomain containing platform helices and ES6 of the 40S central domain. Integration into the 90S is blocked by RNA hybridization with snR30. The snoRNP complex coordinates the recruitment of early assembly factors Krr1-Utp23-Kri1 and ribosomal proteins uS11-uS15, enabling isolated subdomain assembly. Krr1-dependent release of snR30 culminates in integration of the platform into the 90S. Our study reveals the essential role of snR30 in chaperoning central domain formation as a discrete assembly unit externalized from the pre-ribosomal core.

DOI: https://doi.org/10.1038/s41467-025-59656-8