Engineering artificial photosynthetic life-forms through endosymbiosis

The evolutionary origin of the photosynthetic eukaryotes drastically altered the evolution of complex lifeforms and impacted global ecology. The endosymbiotic theory suggests that photosynthetic eukaryotes evolved due to endosymbiosis between non-photosynthetic eukaryotic host cells and photosynthetic cyanobacterial or algal endosymbionts. The photosynthetic endosymbionts, propagating within the cytoplasm of the host cells, evolved, and eventually transformed into chloroplasts. Despite the fundamental importance of this evolutionary event, we have minimal understanding of this remarkable evolutionary transformation. Here, we design and engineer artificial, genetically tractable, photosynthetic endosymbiosis between photosynthetic cyanobacteria and budding yeasts. We engineer various mutants of model photosynthetic cyanobacteria as endosymbionts within yeast cells where, the engineered cyanobacteria perform bioenergetic functions to support the growth of yeast cells under defined photosynthetic conditions. We anticipate that these genetically tractable endosymbiotic platforms can be used for evolutionary studies, particularly related to organelle evolution, and also for synthetic biology applications. The endosymbiotic theory posits that chloroplasts in eukaryotes arise from bacterial endosymbionts. Here, the authors engineer the yeast/cyanobacteria chimeras and show that the engineered cyanobacteria perform chloroplast-like functions to support the growth of yeast cells under photosynthetic conditions.

Automated summary

The evolutionary origin of photosynthetic eukaryotes had a significant impact on the evolution of complex lifeforms and global ecology. The endosymbiotic theory suggests that photosynthetic eukaryotes evolved through endosymbiosis between non-photosynthetic host cells and photosynthetic cyanobacterial or algal endosymbionts. However, our understanding of this important evolutionary transformation is limited. In this study, the authors engineered artificial, genetically tractable photosynthetic endosymbiosis between cyanobacteria and yeast, which can be used for evolutionary studies and synthetic biology applications.