Figure 4: Quorum sensing circuit in V. vulnificus. At low cell densities, expression of SmcR is repressed. At high cell densities, the absence of sRNAs allows the expression of SmcR. Yet, luxT transcription is induced by LuxO at exponential stage and then LuxT represses smcR transcription by direct binding to the upstream region. But this route is not the dominant one controlling SmcR expression. Then, SmcR is expressed and activates production of elastase.