Encapsulation of bacterial photosynthetic reaction centers into viral capsids

Abstract

The final aim of this thesis was to achieve the encapsulation of photosynthetic reaction centers with light harvesting complex 1 from Rhodobacter sphaeroides into viral capsids of bacteriophage P22. To this end, the reaction centers and the capsids had to be isolated and purified first. The capsids are composed of a coat protein forming the stable outer shell and a scaffolding protein driving the self-assembly of the capsids and forming its inner lining. Therefore, scaffolding proteins could be used to introduce the reaction center into the capsids. To achieve that, the scaffolding protein was successfully functionalized with an NTA- maleimide linker for binding with the HisTag of the reaction center's H subunit, creating a reaction center-scaffolding protein complex. By inducing self-assembly of the capsid's components with this complex, the reaction centers were successfully encapsulated. This was confirmed by transmission electron microscopy pictures showing the encapsulated reaction centers. These engineered virus-like particles containing photosystems are therefore a first step towards the assembly of a nanoreactor featuring a photosynthetic reaction center powering a cascade of chemical reactions performed by additionally co-encapsulated enzymes.