tRNA modification landscapes in streptococci: shared losses and clade-specific adaptations.

Fiche publication

Date publication

avril 2026

Journal

Open biology

Auteurs

Membres identifiés du Cancéropôle Est :
Pr MOTORINE Iouri , Dr MARCHAND Virginie

Tous les auteurs :
Tsui HT, Chan CK, Yuan Y, Elias R, Sun J, Marchand V, Jaroch M, Sun G, Manzoor I, Kutchuashvili A, Leszczynska G, Seaton K, Motorin Y, Rice K, Swairjo M, Dedon PC, Winkler ME, de Crécy-Lagard V

Lien Pubmed

https://www.ncbi.nlm.nih.gov/pubmed/41980722

Résumé

tRNA modifications are central to bacterial translational control. Here, we integrated genetics, mass spectrometry, epitranscriptomics and comparative genomics to map the tRNA modification genes of the Gram-positive pathogens Streptococcus mutans and Streptococcus pneumoniae. Both species show a marked loss of modifications dependent on Fe-S enzymes, consistent with a broader trend of Fe-S enzyme reduction in Streptococcus central metabolism. In addition, the D, m1A, m7G, t6A and i6A modifications were mapped in S. pneumoniae tRNAs, and we confirmed that a unique DusB1 enzyme is responsible for the insertion of all the detectable D modifications. We uncovered differences in queuosine (Q) metabolism: while S. mutans synthesizes Q de novo, S. pneumoniae instead salvages preQ₁ and accumulates the epoxy-Q precursor, a strategy shared with multiple other streptococci as revealed by analysis of Q pathways in 1599 sequenced streptococcal genomes. Comparative essentiality profiling of modification genes revealed notable differences, including the essentiality of the N⁶-threonylcarbamoyladenosine (t⁶A) synthesis enzyme TsaE in S. pneumoniae but not in S. mutans, which was confirmed by genetic studies. We found that suppressor mutations in asnS encoding asparaginyl-tRNA synthetase (AsnRS) restored viability to ∆tsaE mutants, albeit with reduced growth. Our finding highlights the functional importance of modifications in the recognition of tRNAs by aminoacyl-tRNA synthetases.