Minding the Gap between Plant and Bacterial Photosynthesis within a Self-Assembling Biohybrid Photosystem.

Abstract

Many strategies for meeting mankind's future energy demands through the exploitation of plentiful solar energy have been influenced by the efficient and sustainable processes of natural photosynthesis. A limitation affecting solar energy conversion based on photosynthetic proteins is the selective spectral coverage that is the consequence of their particular natural pigmentation. Here we demonstrate the bottom-up formation of semisynthetic, polychromatic photosystems in mixtures of the chlorophyll-based LHCII major light harvesting complex from the oxygenic green plant <i>Arabidopsis thaliana</i>, the bacteriochlorophyll-based photochemical reaction center (RC) from the anoxygenic purple bacterium <i>Rhodobacter sphaeroides</i> and synthetic quantum dots (QDs). Polyhistidine tag adaptation of LHCII and the RC enabled predictable self-assembly of LHCII/RC/QD nanoconjugates, the thermodynamics of which could be accurately modeled and parametrized. The tricomponent biohybrid photosystems displayed enhanced solar energy conversion <i>via</i> either direct chlorophyll-to-bacteriochlorophyll energy transfer or an indirect pathway enabled by the QD, with an overall energy transfer efficiency comparable to that seen in natural photosystems.