sRNA-controlled iron sparing response in Staphylococci

Rodrigo Coronel-Tellez (1) , Mateusz Pospiech (2) , Maxime Barrault (1) , Wenfeng Liu (1) , Valérie Bordeau (3) , Christelle Vasnier (2) , Brice Felden (3) , Bruno Sargueil (2) , Philippe Bouloc (1)

1 I2BC - Institut de Biologie Intégrative de la Cellule
2 CiTCoM - UMR 8038 - Cibles Thérapeutiques et conception de médicaments
3 BRM - ARN régulateurs bactériens et médecine

Staphylococcus aureus, a human opportunist pathogen, adjusts its metabolism to cope with iron deprivation within the host. We investigated the potential role of small non-coding RNAs (sRNAs) in dictating this process. A single sRNA, named here IsrR, emerged from a competition assay with tagged-mutant libraries as being required during iron starvation. IsrR is iron-repressed and predicted to target mRNAs expressing iron-containing enzymes. Among them, we demonstrated that IsrR down-regulates the translation of mRNAs of enzymes that catalyze anaerobic nitrate respiration. The IsrR sequence reveals three single-stranded C-rich regions (CRRs). Mutational and structural analysis indicated a differential contribution of these CRRs according to targets. We also report that IsrR is required for full lethality of S. aureus in a mouse septicemia model, underscoring its role as a major contributor to the iron-sparing response for bacterial survival during infection. IsrR is conserved among staphylococci, but it is not ortholog to the proteobacterial sRNA RyhB, nor to other characterized sRNAs down-regulating mRNAs of iron-containing enzymes. Remarkably, these distinct sRNAs regulate common targets, illustrating that RNA-based regulation provides optimal evolutionary solutions to improve bacterial fitness when iron is scarce.

Domaines: Microbiologie et Parasitologie

Rodrigo Coronel-Tellez, Mateusz Pospiech, Maxime Barrault, Wenfeng Liu, Valérie Bordeau, et al.. sRNA-controlled iron sparing response in Staphylococci. Nucleic Acids Research, 2022, 50 (15), pp.8529-8546. ⟨10.1093/nar/gkac648⟩. ⟨hal-03775296v2⟩