MAS1 and infective endocarditis: Although mgrA mutations significantly reduced RNAIII levels [25], [27], the protein also bypasses the quorum sensing system by directly activating the hla gene and repressing spa gene expression via sarS. As with the agr system, MgrA also has a positive effect on capsule synthesis [26], and in a rat infective endocarditis model, MgrA was shown to be the major regulator of capsule formation in vivo[28].