# Yeast pre-rRNA is processed at the A' site

## TL;DR

The study shows that yeast processes pre-ribosomal RNA at a site previously thought to be absent, revealing a conserved mechanism across eukaryotes.

## Contribution

The discovery confirms the presence of the A’ processing site in yeast, challenging prior assumptions and highlighting evolutionary conservation.

## Key findings

- Yeast pre-rRNA is processed at the A’ site in the 5’ETS region.
- This processing site is conserved between single-celled and multicellular eukaryotes.
- The finding challenges previous beliefs about yeast pre-rRNA maturation.

## Abstract

Maturation of the pre-ribosomal RNA (pre-rRNA) in eukaryotes involves a series of processing steps that remove transcribed spacer sequences to produce mature ribosomes. In many organisms two processing sites are located in the 5’external transcribed spacer (5’ETS), along with the site that defines the 5’-end of the 18S rRNA. However, the pre-rRNA processing site near the start site of transcription, known as A’, has long been believed to be absent in the single-celled yeast,
Saccharomyces cerevisiae
. Here we provide evidence that the A’ pre-rRNA processing site is also present in the yeast 5’ETS, confirming conservation among single-celled and multicellular eukaryotes.