# Alarmone ppGpp directly inhibits tRNA-modifying enzyme MnmE in Bacillus subtilis, affecting biofilm

- Published: 2026-11-05 22:25 UTC
- Section: Life & Health › Biology & biochemistry
- Tags: ppGpp alarmone, MnmE TrmE GTPase, tRNA modification, wobble uridine, ribosome profiling, AAG codons, AbrB biofilm repressor, Bacillus subtilis biofilm, codon-specific translation
- URL: https://realtech.media/news/rt-fb7398863521b3f929d5f73a_alarmone_ppgpp_directly/

**In Bacillus subtilis, the stress signal ppGpp acts on a tRNA-modification enzyme, which alters translation at AAG codons and controls biofilm matrix production, authors report.**

![Alarmone ppGpp directly inhibits tRNA-modifying enzyme MnmE in Bacillus subtilis, affecting biofilm](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/083b0a0b29d50b4b.jpg)
*Hannes Grobe, Wikimedia Commons, CC BY-SA 4.0*

Researchers reported in Science Advances that the alarmone guanosine tetraphosphate (ppGpp) directly inhibits MnmE (TrmE), a conserved GTPase that modifies tRNA. The enzyme is required for methylaminomethyl (mnm) modification of wobble uridine [1]. The work links bacterial stress signaling to codon-specific translational control [1].

Using high-resolution ribosome profiling in Bacillus subtilis, the authors found that loss of MnmE selectively increases ribosome pausing at AAG codons. It also reprograms translation of a subset of genes, including small open reading frames [1].

Among them is a previously unrecognized AAG-containing leader peptide that controls expression of the biofilm repressor AbrB [1]. Consistent with this, mnmE mutants produce extracellular matrix constitutively and bypass the biofilm defect of a relA mutant [1]. The authors describe a pathway connecting ppGpp signaling, tRNA modification, codon-specific translation and multicellular development [1].

## Sources

1. [Science Advances](https://doi.org/10.1126/sciadv.aek6976)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-fb7398863521b3f929d5f73a_alarmone_ppgpp_directly/