Fig. 1: Structural characterization of the PSI assembly intermediate.
From: Structure of plant photosystem I in a native assembly state defines PsaF as a regulatory checkpoint
a, Model of pre-PSI-1 with missing PsaF and LHCI. Left: complete model coloured by individual subunits. Right: model of cofactors. The mature PSI model is shown as a semitransparent background layer. b, Left: close-up view of pre-PSI-1 shows the missing PsaF in white cartoon and the PsaA–PsaB region with Pc-binding residues in red. Right: mature PSI with newly identified chlorophyll CLA867 in red cartoon and previously modelled CLA617 and CLA812 in green cartoon; the corresponding cryo-EM density is shown in the close-up view. Mg–Mg distances between chlorophylls are indicated, suggesting a potential excitation energy pathway. c, Left: schematic of pre-PSI-1 and mature PSI protein–protein interactions of membrane subunits. The node size corresponds to relative molecular mass of protein subunits, and the connector length corresponds to the solvent accessible interface area buried between the subunits, calculated with PDBePISA v.1.52 (ref. 12). Interactions of PsaF are shown in blue, and interactions between late assembly subunits are shown in green. PsaJ and Lhca2 are connected via cofactors, shown as a dashed line. Right: surface representation of the model. Only transmembrane subunits are shown: pre-PSI-1 subunits (grey), PsaF (blue) and late assembly subunits of mature PSI (green).
