Artificial photosynthetic cell producing energy for protein synthesis

Samuel Berhanu,Yutetsu Kuruma,Takuya Ueda

doi:10.1038/s41467-019-09147-4

Abstract

Attempts to construct an artificial cell have widened our understanding of living organisms. Many intracellular systems have been reconstructed by assembling molecules, however the mechanism to synthesize its own constituents by self-sufficient energy has to the best of our knowledge not been developed. Here, we combine a cell-free protein synthesis system and small proteoliposomes, which consist of purified ATP synthase and bacteriorhodopsin, inside a giant unilamellar vesicle to synthesize protein by the production of ATP by light. The photo-synthesized ATP is consumed as a substrate for transcription and as an energy for translation, eventually driving the synthesis of bacteriorhodopsin or constituent proteins of ATP synthase, the original essential components of the proteoliposome. The de novo photosynthesized bacteriorhodopsin and the parts of ATP synthase integrate into the artificial photosynthetic organelle and enhance its ATP photosynthetic activity through the positive feedback of the products. Our artificial photosynthetic cell system paves the way to construct an energetically independent artificial cell.

Highlights

Attempts to construct an artificial cell have widened our understanding of living organisms
Light-driven artificial organelle was composed of two kinds of membrane proteins, bacteriorhodopsin and F-type adenosine triphosphate (ATP) synthase (FoF1). bR was isolated from a purple membrane of Halobacterium salinarum by ultra-centrifugation with sucrose density gradient (Fig. 1b and Supplementary Fig. 2)
We show that our artificial cell system containing the artificial organelle was able to first transduce light energy into an electrochemical potential, and convert into the chemical energy of ATP inside giant unilamellar vesicle (GUV)

Summary

Introduction

Attempts to construct an artificial cell have widened our understanding of living organisms. To develop the artificial cell into the energetically independent system, it is necessary to set up a circulating energy-consumption and production system driven by an unlimited external physical or chemical energy source For this purpose, a biomimetic artificial organelle producing adenosine triphosphate (ATP) by collaborating ATP synthase and bacteriorhodopsin is applicable as a rational energy generating system for artificial cells[13,14,15,16,17,18]. Lee et al.[18] performed ATP synthesis using similar photosynthetic artificial organelle, where they demonstrated carbon fixation (in vitro) and actin polymerization within giant unilamellar vesicle (GUV) This result evokes us to apply the artificial organelle into the artificial cell system, i.e., protein synthesis based on the photosynthesized ATP inside GUV. Our artificial cell system enables the self-constitution of its own parts within a structure of positive feedback loop

Methods

Results

Conclusion