Directed Evolution and In Silico Analysis of Reaction Centre Proteins Reveal Molecular Signatures of Photosynthesis Adaptation to Radiation Pressure
Figure 1
Schematic representation of chlamydomonas D1-D2 heterodimer showing the positions of the site-directed D1 aminoacidic substitutions.
Positions of the modified amino acids in the D1 proteins produced by site-directed mutagenesis are viewed in the context of 3D PSII structure. The overall structure of D1 and D2 proteins of PSII and cofactors involved in electron transfer QA, QB, non-heme iron, P680 and OEC, is presented in a view perpendicular to the membrane plane according to [29], [21]. The D1 protein is in light blue and D2 in yellow. The quinone QA, bound to D2, and the quinone QB, bound to D1 protein, are represented in magenta; the non-heme iron in red; the chlorophyll dimer P680 in green. The TyrZ is displayed in sticks and coloured in red and, below, the Mn cluster, the Ca2+ ion and the oxygen atoms of the OEC are shown as orange spheres. The D1 amino acids which were substituted are displayed in space fill representation and coloured in green (for mutations clustering on the IV and V α helices) and purple (for mutations close to the redox-active TyrZ and OEC).