Highly oriented photosynthetic reaction centers generate a proton gradient in synthetic protocells.
Photosynthesis is responsible for the photochemical conversion of light into the chemical energy that fuels the planet Earth. The photochemical core of this process in all photosynthetic organisms is a transmembrane protein called the reaction center. In purple photosynthetic bacteria a simple version of this photoenzyme catalyzes the reduction of a quinone molecule, accompanied by the uptake of two protons from the cytoplasm. This results in the establishment of a proton concentration gradient across the lipid membrane, which can be ultimately harnessed to synthesize ATP. Herein we show that synthetic protocells, based on giant lipid vesicles embedding an oriented population of reaction centers, are capable of generating a photoinduced proton gradient across the membrane. Under continuous illumination, the protocells generate a gradient of 0.061 pH units per min, equivalent to a proton motive force of 3.6 mV⋅min-1Remarkably, the facile reconstitution of the photosynthetic reaction center in the artificial lipid membrane, obtained by the droplet transfer method, paves the way for the construction of novel and more functional protocells for synthetic biology.
Chemistry Department, University of Bari Aldo Moro, I-70126 Bari, Italy.
Emiliano
E
Altamura
Institute for Physical and Chemical Processes, Italian National Research Council, I-70126 Bari, Italy.
Francesco
F
Milano
Chemistry Department, University of Bari Aldo Moro, I-70126 Bari, Italy.
Roberto R
RR
Tangorra
Institute for Physical and Chemical Processes, Italian National Research Council, I-70126 Bari, Italy.
Massimo
M
Trotta
Institute of Chemistry of Organometallic Compounds, Italian National Research Council, I-70126 Bari, Italy.
Omar Hassan
OH
Omar
Science Department, Roma Tre University, I-00146 Rome, Italy.
Pasquale
P
Stano
Chemistry Department, University of Bari Aldo Moro, I-70126 Bari, Italy; fabio.mavelli@uniba.it.
Fabio
0000-0003-0299-0012
F
Mavelli
D058045:Artificial Cells / Q000737:chemistry*; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D008027:Light; D010788:Photosynthesis / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D018892:Proton-Motive Force; D011522:Protons; D011809:Quinones / Q000737:chemistry
D045322:Photosynthetic Reaction Center Complex Proteins; D011522:Protons; D011809:Quinones
artificial cells; giant lipid vesicles; light transduction; photosynthetic reaction center; proton gradient