Abstract
Cyanobacteria harbor unique photoreceptors, designated as cyanobacteriochromes (CBCRs). In this study, we attempted to engineer the chromatic acclimation sensor CcaS, a CBCR derived from the cyanobacterium Synechocystis sp. PCC 6803. The wild-type CcaS induces gene expression under green light illumination and represses it under red light illumination. We focused on the domain structure of CcaS, which consists of an N-terminal transmembrane helix; a GAF domain, which serves as the sensor domain; a linker region (L1); two PAS domains; a second linker region (L2); and a C-terminal histidine kinase (HK) domain. Truncated versions of the photoreceptor were constructed by removing the L1 linker region and the two PAS domains, and fusing the GAF and HK domains with a truncated linker region. Thus constructed “miniaturized CcaSs” were grouped into four distinct categories according to their responses toward green and red light illumination, with some showing improved gene regulation compared to the wild type. Remarkably, one of the miniaturized CcaSs induced gene expression under red light and repressed it under green light, a reversed response to the light signal compared to wild type CcaS. These characteristics of engineered photoreceptors were discussed by analyzing the CcaS structural model.
Highlights
Recent advances in our understanding of photosensing in biological systems have led to the use of photoreceptors as novel genetic tools that regulate gene expression in bioprocess models
Among several CBCRs, we focused on the optogenetic application of the chromatic acclimation sensor CcaS from the unicellular cyanobacterium Synechocystis sp
Various miniaturized CcaSs were created by preparing the corresponding structural genes as follows
Summary
Recent advances in our understanding of photosensing in biological systems have led to the use of photoreceptors as novel genetic tools that regulate gene expression in bioprocess models. Gene expression is promoted by the CcaS-CcaR two-component system under green light exposure and repressed under red light[20]. CcaS-based gene regulation of the autotransporter protein Antigen[43] (Ag43) was employed in the construction of a cell recovery system for non-photosynthetic microorganisms, such as Escherichia coli[5]. These findings highlight the great possibilities in employing CcaS-based green light sensing systems as novel recombinant gene expression tools in bioprocesses, the regulation of gene expression levels by CcaS is not precise and the background expression level under non-inductive, red light illumination is not negligible. Further engineering studies are needed to improve CcaS-directed gene regulation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
