Engineering a rhodopsin-based photo-electrosynthetic system in bacteria for CO2 fixation

Davison, P. A., Tu, W., Xu, J. , Della Valle, S., Thompson, I. P., Neil Hunter, C. and Huang, W. E. (2022) Engineering a rhodopsin-based photo-electrosynthetic system in bacteria for CO2 fixation. ACS Synthetic Biology, 11(11), pp. 3805-3816. (doi: 10.1021/acssynbio.2c00397) (PMID:36264158) (PMCID:PMC9680020)

Abstract

A key goal of synthetic biology is to engineer organisms that can use solar energy to convert CO2 to biomass, chemicals, and fuels. We engineered a light-dependent electron transfer chain by integrating rhodopsin and an electron donor to form a closed redox loop, which drives rhodopsin-dependent CO2 fixation. A light-driven proton pump comprising Gloeobacter rhodopsin (GR) and its cofactor retinal have been assembled in Ralstonia eutropha (Cupriavidus necator) H16. In the presence of light, this strain fixed inorganic carbon (or bicarbonate) leading to 20% growth enhancement, when formate was used as an electron donor. We found that an electrode from a solar panel can replace organic compounds to serve as the electron donor, mediated by the electron shuttle molecule riboflavin. In this new autotrophic and photo-electrosynthetic system, GR is augmented by an external photocell for reductive CO2 fixation. We demonstrated that this hybrid photo-electrosynthetic pathway can drive the engineered R. eutropha strain to grow using CO2 as the sole carbon source. In this system, a bioreactor with only two inputs, light and CO2, enables the R. eutropha strain to perform a rhodopsin-dependent autotrophic growth. Light energy alone, supplied by a solar panel, can drive the conversion of CO2 into biomass with a maximum electron transfer efficiency of 20%.

• Item Type: Articles
• Additional Information: W.E.H. thanks EPSRC (EP/M002403/1 and EP/N009746/1) for the finance support. P.A.D., W.E.H., and C.N.H. gratefully acknowledges funding (BB/M000265/1) from the Biotechnology and Biological Sciences Research Council (United Kingdom). P.A.D. and C.N.H. are supported by European Research Council Synergy Award 854126.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Xu, Dr Jiabao
• Authors: Davison, P. A., Tu, W., Xu, J., Della Valle, S., Thompson, I. P., Neil Hunter, C., and Huang, W. E.
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Journal Name: ACS Synthetic Biology
• Publisher: American Chemical Society
• ISSN: 2161-5063
• ISSN (Online): 2161-5063
• Published Online: 20 October 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in ACS Synthetic Biology 11(11):3805-3816
• Publisher Policy: Reproduced under a Creative Commons license