Molecular Cell
Volume 37, Issue 6, 26 March 2010, Pages 809-820
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Article
Yeast Pre-rRNA Processing and Modification Occur Cotranscriptionally

https://doi.org/10.1016/j.molcel.2010.02.024Get rights and content
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Summary

To better understand yeast ribosome synthesis, we developed techniques for the rapid harvesting and analysis of metabolically labeled cultures. Modeling of the resulting kinetic data allowed predicted lifetimes and processing patterns to be compared with the experimental data. This supported a transcription time for the 35S primary transcripts of ∼170 s at 30°C (∼40 nt s−1), with a high fraction (∼70%) of nascent transcripts cleaved at the early processing sites that generate the 20S precursor to the 18S rRNA. This level of nascent transcript cleavage apparently conflicted with previous reports that modification of yeast pre-rRNA exclusively occurred on released transcripts. A second round of high-resolution kinetic labeling showed that 20S pre-rRNA predominately undergoes methylation as nascent transcripts, whereas the 27S precursor to the 25S/5.8S rRNAs was partially methylated on the nascent transcript. The results demonstrate that quantitative analyses of pre-rRNA processing can yield important biological insights.

Highlights

► Fast labeling was developed to provide kinetic data for modeling of rRNA synthesis ► The model indicated a high degree of cotranscriptional pre-rRNA cleavage ► This suggested that rRNA modification would also occur on nascent transcripts ► Further labeling confirmed substantial methylation of nascent pre-rRNA transcripts

RNA
SYSBIO
DNA

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Present address: Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany