# The DinG exonuclease acts as a primary quality controller to remove unprocessed ribosomal RNAs

## TL;DR

This study shows that the DinG exonuclease helps bacteria by removing unprocessed ribosomal RNA, improving ribosome quality and function.

## Contribution

The study identifies DinG as a primary quality control ribonuclease targeting unprocessed ribosomal RNA in bacteria.

## Key findings

- DinG acts as a 3′- to 5′-exoribonuclease targeting immature ribosomal RNA.
- DinG mutations suppress slow growth in CshC-deficient Listeria monocytogenes.
- DinG interferes with pre-5S rRNA processing mediated by ribonuclease M5.

## Abstract

Bacteria lacking DEAD-box RNA-helicases often show reduced growth and aberrant maturation of ribosomal subunits resulting in fewer active ribosomes. Here, we show that the slow growth observed in a strain lacking the RNA-helicase CshC in the bacterial pathogen Listeria monocytogenes can be suppressed by mutations in the exonuclease DinG. A strain lacking both CshC and DinG increased the number of mature and active ribosomes compared to the parental ΔcshC mutant. DinG acts as a 3′- to 5′-exoribonuclease, targeting immature, unprocessed ribosomal RNA in vitro and in vivo while leaving processed rRNA undisturbed. In addition, DinG directly or indirectly interferes with the ribonuclease M5 mediated pre-5S rRNA processing. We suggest that DinG acts as a primary ribosome quality control ribonuclease that initiates degradation of unprocessed rRNA.

Graphical Abstract