Abstract
BackgroundThe development of multiple gene expression systems, especially those based on the physical signals, such as multiple color light irradiations, is challenging. Complementary chromatic acclimation (CCA), a photoreversible process that facilitates the control of cellular expression using light of different wavelengths in cyanobacteria, is one example. In this study, an artificial CCA systems, inspired by type III CCA light-regulated gene expression, was designed by employing a single photosensor system, the CcaS/CcaR green light gene expression system derived from Synechocystis sp. PCC6803, combined with G-box (the regulator recognized by activated CcaR), the cognate cpcG2 promoter, and the constitutively transcribed promoter, the PtrcΔLacO promoter.ResultsOne G-box was inserted upstream of the cpcG2 promoter and a reporter gene, the rfp gene (green light-induced gene expression), and the other G-box was inserted between the PtrcΔLacO promoter and a reporter gene, the bfp gene (red light-induced gene expression). The Escherichia coli transformants with plasmid-encoded genes were evaluated at the transcriptional and translational levels under red or green light illumination. Under green light illumination, the transcription and translation of the rfp gene were observed, whereas the expression of the bfp gene was repressed. Under red light illumination, the transcription and translation of the bfp gene were observed, whereas the expression of the rfp gene was repressed. During the red and green light exposure cycles at every 6 h, BFP expression increased under red light exposure while RFP expression was repressed, and RFP expression increased under green light exposure while BFP expression was repressed.ConclusionAn artificial CCA system was developed to realize a multiple gene expression system, which was regulated by two colors, red and green lights, using a single photosensor system, the CcaS/CcaR system derived from Synechocystis sp. PCC6803, in E. coli. The artificial CCA system functioned repeatedly during red and green light exposure cycles. These results demonstrate the potential application of this CCA gene expression system for the production of multiple metabolites in a variety of microorganisms, such as cyanobacteria.
Highlights
For the development of bioprocesses using genetically modified bacteria, the physically controllable gene expression systems are recognized as an alternative to the conventional chemical induction system, considering the cost, waste, and recycling of cultivated media
In this study, an artificial chromatic acclimation (CCA) system was successfully developed to realize a multiple gene expression system, which was regulated by two colors, red and green lights, using a single photosensor, the CcaS/CcaR system derived from Synechocystis sp
The designed and constructed artificial CCA gene expression system regulated the expression of two genes, rfp, and bfp, under the red and green light; bfp expression was induced under red light while rfp expression was repressed, and rfp expression was induced under green light while bfp expression was repressed, as we expected
Summary
For the development of bioprocesses using genetically modified bacteria, the physically controllable gene expression systems are recognized as an alternative to the conventional chemical induction system, considering the cost, waste, and recycling of cultivated media. Light-based regulation is ideal for the regulation of cyanobacterial genes, considering the Ariyanti et al Microb Cell Fact (2021) 20:128 availability of various sensing systems. Our research group is engaged in the design of microbial bioprocesses that can be controlled by the light signals, such as the CcaS/CcaR green sensing system derived from Synechocystis sp. NKBG 15041c (NKBG 15041c), to regulate bioprocess using wavelength of marine cyanobacteria [9, 10], and non-photosynthetic bacteria E. coli [11]. The development of multiple gene expression systems, especially those based on the physical signals, such as multiple color light irradiations, is challenging. PCC6803, combined with G-box (the regulator recognized by activated CcaR), the cognate cpcG2 promoter, and the constitutively transcribed promoter, the PtrcΔLacO promoter
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