Small RNA-mediated regulation of the tet(M) resistance gene expression in Enterococcus faecium

Killian Le Neindre (1, 2) , Loren Dejoies (1, 2) , Sophie Reissier (1, 2) , François Guérin (2, 3) , Brice Felden (1, 2) , Vincent Cattoir (2, 1, 3)

1 BRM - ARN régulateurs bactériens et médecine
2 Centre Hospitalier Universitaire de Rennes [CHU Rennes] = Rennes University Hospital [Ponchaillou]
3 CNR - Centre National de Référence de la Résistance aux Antibiotiques [CHU Rennes]

We investigated the role of a novel small RNA expressed in Enterococcus faecium (named Ern0030). We revealed that ern0030 was encoded within the 5’untranslated region of tet(M), a gene conferring tetracycline resistance through ribosomal protection. By RACE mapping, we accurately determined the boundaries of ern0030, which corresponded to Ptet. This upstream sequence of tet(M), Ptet, was previously described within transcriptional attenuation mechanism. Here, Northern blot analyses revealed three transcripts of different lengths (ca. 230, 150 and 100 nucleotides) expressed from Ptet. Phenotypically, the total deletion of ern0030 conferred a decrease in tetracycline MICs that was consistent with gene expression data showing no significant tet(M) induction under tetracycline SIC in ern0030-deleted mutant as opposed to a 10-fold increase of tet(M) expression in the wild-type strain. We investigated the transcriptional attenuation mechanism by toeprint assay. Whereas the expected tet(M) RBS was detected, the RBS of the putative leader peptide was not highlighted by toeprint assay, suggesting the transcriptional attenuation was unlikely. Here, we demonstrate that Ern0030 has a role in regulation of tet(M) expression and propose a novel model of tet(M) regulation alternative or complementary to transcriptional attenuation.

Mots clés: 5’ untranslated region; E. faecium; sRNA; tetracycline resistance

Domaines: Microbiologie et Parasitologie

Killian Le Neindre, Loren Dejoies, Sophie Reissier, François Guérin, Brice Felden, et al.. Small RNA-mediated regulation of the tet(M) resistance gene expression in Enterococcus faecium. Research in Microbiology, 2022, 173 (4-5), pp.103941. ⟨10.1016/j.resmic.2022.103941⟩. ⟨hal-03660105⟩