Analysis of the CodY RNome reveals RsaD as a stress-responsive riboregulator of overflow metabolism in Staphylococcus aureus

Yoann Augagneur (1) , Alyssa N King (2) , Noëlla Germain-Amiot (1) , Mohamed Sassi (1) , John W Fitzgerald (2) , Gyan S Sahukhal (3) , Mohamed O Elasri (3) , Brice Felden (1) , Shaun R Brinsmade (2)

1 BRM - ARN régulateurs bactériens et médecine
2 GU - Georgetown University [Washington]
3 USM - University of Southern Mississippi

In Staphylococcus aureus, the transcription factor CodY modulates the expression of hundreds of genes, including most virulence factors, in response to the availability of key nutrients like GTP and branched-chain amino acids. Despite numerous studies examining how CodY controls gene expression directly or indirectly, virtually nothing is known about the extent to which CodY exerts its effect through small regulatory RNAs (sRNAs). Herein, we report the first set of sRNAs under the control of CodY. We reveal that staphylococcal sRNA RsaD is overexpressed> 20-fold in a CodY-deficient strain in three S. aureus clinical isolates and in S. epidermidis. We validated CodY-dependent regulation of rsaD and demonstrate that CodY directly represses rsaD expression by binding the promoter. Using a combination of molecular techniques, we show that RsaD post-transcriptionally regulates alsS (acetolactate synthase) mRNA and enzyme levels. We further show that RsaD redirects carbon overflow metabolism, contributing to stationary phase cell death during exposure to weak acid stress. Taken together, our data delineate a role for CodY in controlling sRNA expression in a major human pathogen and indicate that RsaD may integrate nutrient depletion and other signals to mount a response to physiological stress experienced by S. aureus in diverse environments.

Mots clés: post-transcriptional; physiology; Gram-positive; regulation; sRNA; staphylococci; physiology Accepted Article

Domaines: Sciences du Vivant [q-bio]; Microbiologie et Parasitologie

Yoann Augagneur, Alyssa N King, Noëlla Germain-Amiot, Mohamed Sassi, John W Fitzgerald, et al.. Analysis of the CodY RNome reveals RsaD as a stress-responsive riboregulator of overflow metabolism in Staphylococcus aureus. Molecular Microbiology, 2020, 113 (2), pp.309-325. ⟨10.1111/mmi.14418⟩. ⟨hal-02397672⟩