An evolutionary optimization of a rhodopsin-based phototrophic metabolism in Escherichia coli

Microbial Cell Factories

Kyoo Heo¹  Yeong-Jae Seok¹  Pil Kim²  Jihoon Park²  Kwang-Hwan Jung³  Ah Reum Choi³  Hyun Ju Kim⁴  Sang Jun Lee⁴  Hyun Aaron Kim⁵  Haeyoung Jeong⁶ 

[1] Department of Biological Sciences, Seoul National University;Department of Biotechnology, The Catholic University of Korea;Department of Life Sciences, Sogang University;Department of Systems Biotechnology, Chung-Ang University;Hana Academy Seoul;Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB);

关键词: Adaptive laboratory evolution;    Strain optimization;    Chemotroph;    Phototroph;    Rhodopsin;    Proton pumping;   

DOI  :  10.1186/s12934-017-0725-6

来源: DOAJ

【 摘 要 】

Abstract Background The expression of the Gloeobacter rhodopsin (GR) in a chemotrophic Escherichia coli enables the light-driven phototrophic energy generation. Adaptive laboratory evolution has been used for acquiring desired phenotype of microbial cells and for the elucidation of basic mechanism of molecular evolution. To develop an optimized strain for the artificially acquired phototrophic metabolism, an ancestral E. coli expressing GR was adaptively evolved in a chemostat reactor with constant illumination and limited glucose conditions. This study was emphasized at an unexpected genomic mutation contributed to the improvement of microbial performance. Results During the chemostat culture, increase of cell size was observed, which were distinguished from that of the typical rod-shaped ancestral cells. A descendant ET5 strain was randomly isolated from the chemostat culture at 88-days. The phototrophic growth and the light-induced proton pumping of the ET5 strain were twofold and eightfold greater, respectively, than those of the ancestral E. coli strain. Single point mutation of C1082A at dgcQ gene (encoding diguanylate cyclase, also known as the yedQ gene) in the chromosome of ET5 strain was identified from whole genome sequencing analysis. An ancestral E. coli complemented with the same dgcQ mutation from the ET5 was repeated the subsequently enhancements of light-driven phototrophic growth and proton pumping. Intracellular c-di-GMP, the product of the diguanylate cyclase (dgcQ), of the descendant ET5 strain was suddenly increased while that of the ancestral strain was negligible. Conclusions Newly acquired phototrophic metabolism of E. coli was further improved via adaptive laboratory evolution by the rise of a point mutation on a transmembrane cell signaling protein followed by increase of signal molecule that eventually led an increase proton pumping and phototrophic growth.

【 授权许可】

Unknown