LitR directly upregulates autoinducer synthesis and luminescence in .

LitR is a master-regulator of transcription in the and quorum sensing (QS) systems of bacteria from and genera. Here, we for the first time directly investigated the influence of LitR on gene expression in the QS system of psychrophilic bacteria . Investigated promoters were fused with reporter genes cassette in a heterological system of cells, was introduced into the cells under control of P promoter. LitR has been shown to upregulate genes of autoinducer synthase (), luciferase and reductase (), and this effect doesn't depend on presence of gene. To a much lesser degree, LitR induces , but not the the main regulator. Enhanced expression leads to an increase in a LuxI-autoinducer synthesis and a subsequent LuxR-mediated activation of the QS system. Effect of LitR on transcription depends on -box sequence in promoter even in absence of (-box is binding site of LuxR). The last finding indicates a direct interaction of LitR with the promoter in the -box region. Investigation of the effect of LitR on QS systems of mesophilic and psychrophilic showed direct -independent upregulation of and genes. To a lesser degree, it induces and . Therefore, we assume that the main role of LitR in cross-interaction of these three QS systems is stimulating the expression of .