Regulatory RNA III (RNAIII) (RNAIII)

Regulatory RNA III (RNAIII) is the primary effector molecule of the accessory gene regulator (agr) quorum-sensing system in Staphylococcus aureus (PubMed: 21957601; PubMed: 11609781). It is a complex, 514-nucleotide dual-function RNA that serves both as a transcript for the delta-hemolysin (hld) peptide and as a trans-acting regulatory RNA (PubMed: 17540507). RNAIII coordinates the switch between the early colonization phase, characterized by the expression of surface adhesins, and the later invasive phase, characterized by the secretion of toxins and proteases (PubMed: 27550441). By base-pairing with target mRNAs, RNAIII represses the translation of surface proteins such as Protein A (spa) and staphylocoagulase (coa) while activating the translation of exotoxins like alpha-hemolysin (hla) (PLOS Pathogens: e1000809). As a central regulator of MRSA pathogenesis, RNAIII is a prominent target for anti-virulence therapies that aim to attenuate bacterial infection without exerting the high selective pressure typical of traditional antibiotics (Frontiers in Microbiology: 9:18). Therapeutic strategies under development include the RNAIII-inhibiting peptide (RIP) and its derivatives, which disrupt the signaling required for RNAIII synthesis, thereby preventing biofilm formation and toxin production in clinical isolates (PubMed: 11609781; Antimicrob Agents Chemother: 52(6):2205-11).

Other names

Staphylococcus aureus RNAIIIagr effector RNAhld transcriptAccessory gene regulator effector RNAIIIDelta-hemolysin transcript

Inhibition of the quorum-sensing-mediated synthesis of RNAIII or blocking its antisense interaction with target mRNAs to suppress bacterial virulence and biofilm formation.