Brazell, K. M. | bioRxiv Science

bioRxiv2026

Integrative Nanopore and Illumina sequencing reveals age-associated tRNA modification and CCA-tail dynamics in yeast

Aging is characterized by a progressive loss of proteostasis. Transfer RNAs (tRNAs) are essential regulators of translation, yet their dynamics during aging remain poorly understood due to challenges in sequencing highly modified RNAs. Here we present a benchmarked Nanopore direct RNA sequencing (RNA004 chemistry) resource that profiles the Saccharomyces cerevisiae tRNAome during replicative aging at single-molecule resolution. Using in vitro transcribed tRNA controls, we establish modification detection thresholds and validate key findings with orthogonal Illumina sequencing. While overall tRNA abundance remains largely stable, our resource reveals age-associated terminal A cleavage at the 3' CCA tail of mature tRNAs, targeted T-loop and anticodon modification changes, and single-molecule evidence of modification co-occurrence. This dataset provides a resource for exploring tRNA regulation, translation fidelity, and longevity.

genomics↗

bioRxiv2026

Temozolomide Induces Aberrant RNA Alkylation and Widespread Translational Repression

Temozolomide (TMZ) is a frontline alkylating chemotherapy, yet its direct impact on RNA modification and global translation dynamics remains poorly understood. Here, we demonstrate that TMZ induces pervasive RNA alkylation causing severe translational impairment. TMZ directly deposits aberrant methyl groups onto single-stranded mRNA in vitro, creating physical lesions that lower translational efficiency. In glioblastoma cells, acute TMZ exposure triggers a rapid, widespread accumulation of m7G on cellular RNAs, leading to the significant attenuation of global protein synthesis. Nanopore direct RNA sequencing identified distinct guanine-specific error signatures and sequence context preferences associated with TMZ-induced damage. Using a quantitative yeast spike-in ribosome profiling strategy, we mapped this translational repression at transcript-level, revealing a global downregulation of translational efficiency. This widespread repression disproportionately targets highly interconnected networks essential for cellular proliferation, specifically chromosome organization. We show that the severity of this translational repression is driven by a transcript's coding guanine density, stability and translation initiation speed. Together, our findings suggest that TMZ-induced alkylation targets stable, highly translated, guanine-rich transcripts. This establishes aberrant RNA methylation and subsequent translational arrest as a potential mechanism of temozolomide cytotoxicity.

biochemistry↗