In Vivo Programmed Gene Expression Based on Artificial Quorum Networks

Abstract

bThe quorum sensing (QS) system, as a well-functioning population-dependent gene switch, has been widely applied in many gene circuits in synthetic biology. In our work, an efficient cell density-controlled expression system (QS) was established via engineering of the Vibrio fischeri luxI-luxR quorum sensing system. In order to achieve in vivo programmed gene expression, a synthetic binary regulation circuit (araQS) was constructed by assembling multiple genetic components, including the quorum quenching protein AiiA and the arabinose promoter P araBAD , into the QS system. In vitro expression assays verified that the araQS system was initiated only in the absence of arabinose in the medium at a high cell density. In vivo expression assays confirmed that the araQS system presented an in vivo-triggered and cell density-dependent expression pattern. Furthermore, the araQS system was demonstrated to function well in different bacteria, indicating a wide range of bacterial hosts for use. To explore its potential applications in vivo, the araQS system was used to control the production of a heterologous protective antigen in an attenuated Edwardsiella tarda strain, which successfully evoked efficient immune protection in a fish model. This work suggested that the araQS system could program bacterial expression in vivo and might have potential uses, including, but not limited to, bacterial vector vaccines.

An Engineered Device for Indoleacetic Acid Production under Quorum Sensing Signals Enables Cupriavidus pinatubonensis JMP134 To Stimulate Plant Growth

“…A genetic circuit with a positive feedback for cell density-dependent control of gene expression was constructed with the QS system from marine bacterium V. fischeri . ,, luxI and luxR genes and P lux promoter, identified as key elements of the QS system in this bacterium, have been used previously to construct artificial cell-to-cell communication systems. ,− We constructed a genetic circuit able to produce and respond to N -(3-oxohexanoyl)- l -homoserine lactone, 3-oxo-C6-HSL, increasing the transcription of the target gene, GFP (Figure A). The strain harboring this circuit was called P lux - luxI -GFP (Figure A), and was able to synthesize 3-oxo-C6-HSL (Supplementary Figure S1).…”

“…of QS system in this bacterium, have been used previously to construct artificial cell-to-cell communication systems 14,[24][25][26][27] . We constructed a genetic circuit able to produce and respond to N-(3-Oxohexanoyl)-L-homoserine lactone, 3-oxo-C6-HSL, increasing the transcription of target gene, GFP (Fig.…”

Site-Directed Mutagenesis to Improve Sensitivity of a Synthetic Two-Component Signaling System

“…As the field of synthetic biology grows, scientists and engineers are developing new tools to control living cells, thus expanding the range of input signals that can be used to control cellular gene expression. Recent advances include synthetic systems controlled by time [ 1 ], cellular density [ 2 ], and light [ 3 ]. These synthetic systems can be used to study a diverse collection of biological phenomena such as spatial dynamics, signal transmission patterns, and the effects seen from oscillatory input on signaling networks [ 4 ].…”