Fiche publication
Date publication
novembre 2025
Journal
Microbiology spectrum
Auteurs
Membres identifiés du Cancéropôle Est :
Pr MOTORINE Iouri
,
Dr MARCHAND Virginie
Tous les auteurs :
Tseduliak V-M, Koshla O, Mulartschyk SN, Marchand V, Motorin Y, Helm M, Ostash B
Lien Pubmed
Résumé
() J1074 is one of the preferred streptomycete chassis strains for the expression of specialized metabolite biosynthetic gene clusters. Leucyl tRNA gene is one of the regulatory switches that, through delayed translation of its cognate codon UUA, confines the production of specialized metabolites to a stationary phase. An integral step in the maturation of the tRNA is its post-transcriptional tRNA modifications (PTTMs), which are poorly understood. Exploring the installation of BldA PTTMs may reveal their cross-talk with antibiotic biosynthesis regulatory pathways and offer new ways to manipulate specialized metabolism in . In this work, we focused on the J1074 gene , coding for a SPOUT family tRNA methyltransferase homologous to TrmL that methylates the ribose residue of uridine (2'-O-methyluridine or Um) at the wobble position of leucyl tRNA. First, we revisited the diversity of modified nucleosides for the wild-type strain and suggest that wobble uridine in tRNA is in the form of sUm. Wobble uridine hypermodifications, such as mnmsU (5-methylaminomethyl-2-thiouridine), cmnmsU (5-carboxymethylaminomethyl-2-thiouridine), and cmnmUm (5-carboxymethylaminomethyl-2'-O-methyluridine), found in enterobacteria, could not be confirmed for J1074. Second, while an knockout did not diminish the formation of sUm, it did lead to a strong decrease in the abundance of Um in total nucleoside hydrolyzates. The loss of Um32 in leucyl tRNA, as well as the loss of 2'-O-methylated cytosine 32 (Cm32) in prolyl tRNA, was confirmed by RiboMethSeq profiling of the mutant. Our results are reminiscent of the abrogated TrmJ function responsible for position 32 C/U methylation in Gram-negative bacteria. Notably, our findings are the first demonstration of TrmJ-controlled methylation in Gram-positive bacteria. This work expands the understanding of tRNA modification systems in streptomycetes and their potential impact on specialized metabolite production. Post-transcriptional modifications are ubiquitous in tRNAs, where they play important structural and regulatory roles. As the types of modified nucleosides and their genetic control differ even between closely related bacterial taxa, there is a need to study them across the entire phylogenetic tree. We recently initiated studies of genetics and chemistry of tRNA modifications in streptomycetes, one of the most prolific producers of specialized metabolites of immense practical value (antibiotics, anticancer drugs, to name just a few). A point of special interest was the modifications of leucyl tRNA, the only one capable of decoding the rarest in codon UUA. In a search for a TrmL homologue responsible for 2'-O-methylation of the wobble nucleoside 34 (U) ribose of tRNA, we probed the function of gene . knockout led to the loss of 2'-O-methylated uridine 32 (Um) in leucyl tRNA and 2'-O-methylated cytosine 32 (Cm) in prolyl tRNA. This result, as well as analysis, suggests parallels between Xnr_5296 and the TrmJ enzyme responsible for U/C methylation at position 32 of glutaminyl tRNA and tRNA, methionyl tRNA, seryl tRNA, and tryptophanyl tRNA, although the counterpart methylates different tRNA species. Thus, our work reveals previously unreported tRNA modification and its gene in and serves as a stepping stone to further interrogate the functions of highly paralogous SPOUT family methyltransferases in this important bacterial genus.
Mots clés
Streptomyces albidoflavus (albus) J1074, bioactive natural products, genes, methyltransferases, post-transcriptional tRNA modifications, regulation, tRNA
Référence
Microbiol Spectr. 2025 11 26;:e0219225
