A dual sRNA inStaphylococcus aureusinduces a metabolic switch responding to glucose consumption

Abstract

30Pathogenic bacteria must rapidly adapt to ever-changing environmental signals or nutrient 31 availability resulting in metabolism remodeling. The carbon catabolite repression represents 32 a global regulatory system, allowing the bacteria to express genes involved in carbon 33 utilization and metabolization of the preferred carbon source. In Staphylococcus aureus, 34 regulation of catabolite repressing genes is mediated by the carbon catabolite protein A 35 (CcpA). Here, we have identified a CcpA-dependent small non-coding RNA, RsaI that is 36 inhibited by high glucose concentrations. RsaI represses the translation of mRNAs encoding 37 a major permease of glucose uptake, the FN3K enzyme that protects proteins against 38 damages caused by high glucose concentrations, and IcaR, the transcriptional repressor of 39 exopolysaccharide production. Besides, RsaI regulates the activities of other sRNAs 40 responding to the uptake of glucose-6 phosphate or NO. Finally, RsaI inhibits the expression 41 of several enzymes involved in carbon catabolism pathway, and activates genes involved in 42 energy production, fermentation and NO detoxification when the glucose concentration 43 decreases. This multifunctional RNA provides a signature for a metabolic switch when 44 glucose is scarce and growth is arrested. 45 46 47 48All bacteria require a carbon source, providing energy for their growth, division, and for the 49 synthesis of all macromolecules. Besides, pathogenic bacteria during the infectious process 50 of the host, must cope with hostile conditions such as nutrient deficiency, temperature, 51 oxidative and osmotic shocks, and must overcome innate immune responses. For instance, 52Staphylococcus aureus uses carbohydrates to grow under high NO and anaerobiosis (Vitko 53 et al., 2016). To survive in these complex environments and to counteract the host defense, 54 S. aureus produces a plethora of virulence factors. The synthesis of these factors is fine-55 tuned by intricate interactions between multiple regulators involving both proteins and RNAs 56 (Novick, 2003). Additionally, biosynthetic intermediates, generated from the central 57 metabolism of S. aureus, have strong impacts on the synthesis of virulence factors. Besides, 58 several metabolite-sensing regulatory proteins (CcpA, CodY, Rex and RpiR) act as key 59 regulatory factors to coordinate the synthesis of genes involved in metabolic pathways, in 60 stress responses, and in pathogenesis (Somerville and Proctor, 2009; Richardson et al., 61 2015). Through the adaptation of the metabolism of the bacteria to specific host 62 microenvironment, these proteins contribute to S. aureus pathogenesis (Richardson et al., 63 2015). 64Among these proteins, the carbon catabolite protein A (CcpA) acts as a catabolite 65 regulator, allowing the bacteria to use the preferred carbon source (i.e., glucose) in a 66 hierarchical manner (Seidl et al., 2008a;Seidl et al., 2009). CcpA belongs to the LacI 67 repressor family and binds to a specific DNA sequence, called the cre ...

Navigation through the twists and turns of RNA sequencing technologies: Application to bacterial regulatory RNAs

“…Hence, an elegant strategy is to use an sRNA as bait to co-purify all interacting RNAs. MAPS (MS2-affinity purification coupled with RNA sequencing) technology was performed in several organisms like E. coli [4,64,74,75], Salmonella Typhimurium [76] and S. aureus [77,78]. Detailed protocols are available [79,80].…”