Development of a reversible regulatory system for gene expression in the cyanobacterium Synechocystis sp. PCC 6803 by quorum-sensing machinery from marine bacteria

Histidine kinases are common sensory proteins used to detect environmental changes in bacteria. They respond specific stimuli via a signal-input domain and alter gene expression through cognate response regulator. The modulation/control of transcriptional regulation cyanobacteria is important reinforce the production useful target compounds photosynthesis without altering growth profiles. For instance, heavy metal ions (Ni2+ Cu2+), chemical inducers (IPTG), volatile compound (toluene) have been previously applied regulate cyanobacteria. However, most systems/regulators only able once because it impossible eliminate them from medium. To construct reversible system, chimeric sensor, VanN_SphS, was developed by fusing signal input quorum-sensing (QS) VanN, Vibrio anguillarum, responding N-3-hydroxyhexanoyl-L-homoserine lactone (OHC6-HSL), with kinase SphS, phosphate-deficiency sensor cyanobacterium Synechocystis sp. PCC 6803. After cells, responses various N-acyl-homoserine-lactones (AHLs) were evaluated measuring alkaline phosphatase (AP) activity, which regulated SphS. VanN_SphS responded OHC6-HSL repressed AP activity. Then, coexpression AHLs-degradation enzyme, Aii20J, lactonase Tenacibaculum 20J, resumed This first report on use AHL-mediated Synechocystis, could be future for controlled cyanobacterium.