Fig. 1
From: Artificial photosynthetic cell producing energy for protein synthesis
Light-driven adenosine triphosphate (ATP) synthesis by artificial organelle. a Schematics of the artificial photosynthetic cell encapsulating artificial organelle, which consists of bacteriorhodopsin (bR) and FoF1-ATP synthase (FoF1). Synthesized ATP are consumed as substrates for messenger RNA (mRNA) (➀), as energy for phosphorylation of guanosine diphosphate (GDP) (➁) or as energy for aminoacylation of transfer RNA (tRNA) (➂). b Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of purified bR and FoF1. The positions of molecular markers and FoF1 component proteins are indicated beside the gels. c Light-driven proton-pump activity of bR reconstituted in a proteoliposome (PL). Proton-pump activity of bR was measured by monitoring the proton concentration at the outside of bR-PLs where fluorescent proton-sensor ACMA (9-amino-6-chloro-2-methoxy acridine) was added. We defined as ΔpH = pH (original, outside) − pH (after illumination, outside). The ΔpH caused by bR activity was measured with the various bR concentrations as indicated. White and gray areas indicate light ON and OFF, respectively. An uncoupler, FCCP (carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone), was used as a control experiment. d ATP synthesis activity of FoF1 reconstituted as FoF1-PLs. ATP synthesis reactions were initiated by adding FoF1-PLs at 30 s with various FoF1 concentrations, as indicated. The synthesized ATP was measured by means of luciferin and luciferase (see Methods section for the experiment details). FCCP was used for control. e Light-driven ATP synthesis. The amount of the photosynthesized ATP by bRFoF1-PLs, which was constituted in various proportions of bR against FoF1, were measured by luciferin and luciferase. FCCP and dark conditions were also performed as controls. The inset indicates initial rate of the each PL. f Light-driven ATP synthesis inside giant unilamellar vesicle (GUV). bRFoF1-PLs were illuminated inside GUVs in the presence or absence of proteinase K (PK) that degrades the FoF1. The in vitro experiment was also performed for comparison. ***p < 0.001. P values were from two-sided t-test. All experiments were repeated at least three times, and their mean values and standard deviations (S.D.) are shown. Source data are provided as a Source Data file
