The Small RNA Teg41 Regulates Expression of the Alpha Phenol-Soluble Modulins and Is Required for Virulence in Staphylococcus aureus

Abstract

Small RNAs (sRNAs) remain an understudied class of regulatory molecules in bacteria in general and in Gram-positive bacteria in particular. In the major human pathogen Staphylococcus aureus, hundreds of sRNAs have been identified; however, only a few have been characterized in detail. In this study, we investigate the role of the sRNA Teg41 in S. aureus virulence. We demonstrate that Teg41, an sRNA divergently transcribed from the locus that encodes the cytolytic alpha phenol-soluble modulin (αPSM) peptides, plays a critical role in αPSM production. Overproduction of Teg41 leads to an increase in αPSM levels and a corresponding increase in hemolytic activity from S. aureus cells and cell-free culture supernatants. To identify regions of Teg41 important for its function, we performed an in silico RNA-RNA interaction analysis which predicted an interaction between the 3′ end of Teg41 and the αPSM transcript. Deleting a 24-nucleotide region from the S. aureus genome, corresponding to the 3′ end of Teg41, led to a 10-fold reduction in αPSM-dependent hemolytic activity and attenuation of virulence in a murine abscess model of infection. Restoration of hemolytic activity in the Teg41Δ3′ strain was possible by expressing full-length Teg41 in trans. Restoration of hemolytic activity was also possible by expressing the 3′ end of Teg41, suggesting that this region of Teg41 is necessary and sufficient for αPSM-dependent hemolysis. Our results show that Teg41 is positively influencing αPSM production, demonstrating for the first time regulation of the αPSM peptides by an sRNA in S. aureus. IMPORTANCE The alpha phenol-soluble modulins (αPSMs) are among the most potent toxins produced by Staphylococcus aureus. Their biological role during infection has been studied in detail; however, the way they are produced by the bacterial cell is not well understood. In this work, we identify a small RNA molecule called Teg41 that plays an important role in αPSM production by S. aureus. Teg41 positively influences αPSM production. The importance of Teg41 is highlighted by the fact that a strain containing a deletion in the 3′ end of Teg41 produces significantly less αPSMs and is attenuated for virulence in a mouse abscess model of infection. As the search for new therapeutic strategies to combat S. aureus infection proceeds, Teg41 may represent a novel target.

RNA-Sequencing Analyses of Small Bacterial RNAs and their Emergence as Virulence Factors in Host-Pathogen Interactions

“…In a murine abscess model, sRNA Teg41 was identified as being required for virulence. Teg41 (200 nt) positively influences αPSM production and, therefore, the hemolytic activity of S. aureus [109]. A Staphylococcus strain carrying a mutated Teg49 sRNA exhibited a reduced bacterial load compared to the wild-type S. aureus strain.…”

Comparative Transcriptomic and Functional Assessments of Linezolid-Responsive Small RNA Genes in Staphylococcus aureus

“…It increases the translation of Sbi immune evasion molecules, and consequently weakens the innate and adaptive immune responses (22,23). In addition to these examples, only a handful of sRNAs have been assessed for functions, including identifying their targets (6,7,(24)(25)(26)(27)(28)(29)(30).…”

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

“…For instance, RNAIII-the sRNA effector of the accessory gene regulator (Agr) quorum sensing system-adjusts toxin expression in response to population density via the regulation of many direct and indirect targets (Balaban & Novick, 1995;Boisset et al, 2007;Cheung, Wang, Khan, Sturdevant, & Otto, 2011;Marroquin et al, 2019;Novick et al, 1993;Queck et al, 2008;Recsei et al, 1986). Other sRNAs in S. aureus have been discovered to mediate responses to changing environmental conditions (Nielsen et al, 2011), prompt the synthesis of virulence-associated factors (Manna et al, 2018;Romilly et al, 2014;Zapf et al, 2019), influence antibiotic resistance (Eyraud, Tattevin, Chabelskaya, & Felden, 2014), and adjust metabolism during growth (Bohn et al, 2010a;Geissmann et al, 2009). Employing the regulatory influence of sRNAs to adjust cellular physiology is advantageous.…”