Computational characterization of the all-atom structure and the calcium binding sites of the LH1–RC core complex from Thermochromatium tepidum

The all-atom model of the photosynthetic core complex composed of the light-harvesting system (LH1) and the reaction center (RC) from a thermophilic purple bacterium Thermochromatium tepidum is constructed. We compare the structural parameters of this complex embedded into the lipid bilayer to those reported for the recently resolved crystal structure of the LH1–RC. We focus on the local structure of the binding sites of the calcium ions regulating stability and optical spectra of the core complex. We show the differences between the computationally derived model and the crystal structure at the extramembrane region of the LH1 polypeptides where the calcium binding sites are located.